tips to help me stop ruining my economy

1. Everything you build, takes money from your wallet when it's build, not before - stop building tons of ships.
2. If you colonize world with high climate hazard, you have to pay for life support, until they start making some profit - stop colonizing like maniac.
3. Prototypes - every first ship of paricular design costs 3 or 4 times more - stick to one or two design.

Sure I'll give a few pointers.

First with ship building - Prototyping is expensive, so take advantage of the first turn free prototyping. Make hull designs for every ship class available. This will usually let you avoid prototyping costs for the first 20 turns or so.
Researching Orbital dry docks is also recommended, as it lets you retrofit designs with higher end weapons based on what the ship is setup for. Ie UV to X-ray lasers, Plasma cannons to Fusion and Antimatter cannons. This again lets you avoid prototype costs.

Try not to build too many fleets at once, that's an easy way to go into quick debt, as the money for the ships is subtracted from saving once the ship is built, not when its ordered.
Keep in mind that in early game, unless you are morrigi, its advantageous to not use full fleets for surveying. Build one or 2 full fleets and several smaller fleets. Systems with 1-3 planets in them will survey in a handful of turns with a 4-5 ship fleet, and system without asteroids have a lower chance of random encounters(no Asteroid monitors, Swarm or relics) and only need a few ships. Save your full fleets for system that would otherwise take several turn(5+) to survey.
Its also good to note that Drone and Battlerider ships survey faster, though you likely won't have riders during the survey phase.
Its also very easy to go bankrupt in the DN era, as they often have prototype costs of 5+ million credits, so keep an eye on prototype costs.

Colony fleets build infrastructure and population faster the more colony ships are in them, so make sure you have at least 4 in your colony fleets. I tend to have 3 colony fleets running before turn 20, and will build up to another 3 if there are lots of planets to get.
If the planets have a high climate hazard(400+) Its a good idea to research biome colonizers. They aren't as crazy as they were in Prime, but they trade a bit less infrastructure per trip for sped up terraforming. Civilian stations at level 2 and 3 also have a terraforming module that can be built, significantly lowering the terraform cost, which is a good idea for system with multiple high CH planets.

Lastly is trade development, I tend to start this around turn 30. Build civ stations around large planets, you can make a trade good per 100 mil pop so the bigger the better. Don't put them everywhere as your high trade planets will be useless for building. Trade isn't as crazy as in Prime, but a few good systems will give you 300k-1 mil per turn by turn 60 if you do it right. Having a few resource rich system to use as ship building hubs will let you utilize more system for trade, and you can get even higher. Oh and stay away from mega freighters until later, there main benefit is to carry 2 trade goods per dock instead of one, but they cost 5x as much as a normal freighter. They automatically replace normal freighters when built, so it's often the most economical to built them after you economy has taken off. At that point they are usually cheaper than upgrading the civilian stations further, so they will double the trade good load of the docks.

Make sure you are defining provinces as well, it increases the value of a trade good when it crosses province lines.

Other than that, I'd need to know more about what you are doing to help out, but I hope this will be of some assistance.

First stop trying to do everything all at once, even with 10 starting planets, you can get into trouble very quickly (as you've discovered).

Remember in SotS Prime you started with Destroyer class ships and you build lots of them. Battleriders are the equivalent to Destroyers, but need a "Carrier" to move to other systems. (...and need to be researched as well, both Battlerider tech and carrier tech). This is the "cruiser" age, your ships will cost more.

As A-N has said, prototype first turn every class (it's FREE) to your specifications, but after that be careful about prototyping since that can get expensive fast if you don't have a solid economy and you do it often for every little change. Research Orbital dry docks so you can do weapon (and some modules) upgrades, but you can't change engine or armor on old ships. Just weapons of type (energy to energy and ballistic to ballistic etc) and modules (since they tac onto the ships externally). Do not think of Retrofitting as a full on ship redesign, it isn't. It is only weapons as I've explained and modules. However this keeps your ships from becoming to obsolete and reusable for much longer then before.

Colonize slowly, or use the incentive / Stimulus option and have the AI do it for you (civilian), wait for them to develop the planet for you and once it's reaches a viable age, coax it back into your empire. Warning using Stimulus takes patience and time, however it can save you a tremendous savings over time and cause you go get big dividends later. SotS 2 is a slower paced more thoughtful game then SotS Prime was. Don't be in a hurry, depending on the map and opponents the game can literally last thousands of turns. If you want a quick bang bang game, play on a much smaller map with less players, otherwise, enjoy the ride!

Remember when you colonize to do pretty much as A-N has suggested. I would make the additional suggestion that if you want to hammer colonization directly that you should research the techs to make it easier for you, like the larger class colony ships. Use multiple colony ships to build them up faster, when (if) a fleet of colony ships are available, but no planets are and you have one in the "oven", send it over to assist the building of the current colony!

Remember to setup what fleets you have to patrol and guard your systems. You don't really need to have one fleet for every system/planet you own, use the mission system! This is especially effective for Hivers and other FAST movers (like Morrigi fleets with the Gravboat in them etc), or Sol Force etc.

As A-N said, the more ships you have in survey fleets (especially those that carry drones and BR's), the faster you can survey. This is especially useful for LARGE solar systems.

With 10 planet empires at start, you should on average be earning (as in goes in the bank) 1mil a turn, unless you are in some kind of emergency mode. Saving for that rainy day when it's time to revamp the fleet with new prototypes and so on, or the placement of defenses or bases etc. Remember not every system needs a class 5 Naval station and Research and Civilian station, they can get VERY expensive and take a LONG time to build. Speaking of stations etc, remember to use more then one Construction ship, they stack and will let you build those big stations in a reasonable period of time.

Hope that helps along with what others have said. Primarily just remember, this is a thinking players game, slow down, take time, be patient and ....think! My favorite saying works well for this game...work smarter, not harder.

Good luck, and enjoy!

Here is a nice thread on the Kerberos forums on what players do their first 10 turns, perhaps that will help you as well:

First 10 turns

Ok here it goes.

1. For Colonizers I built 1 fleet consisting of 1 command, 2 supply and all the rest colonizers.

2. I refit all my upcoming ships with energy weapons because mass drivers don't work against specters.

3. I only colonize the best planet in a system initially. While I build it up, my scout fleet is looking for the next system.

4. I build a second colony fleet with a command, one supply, and just a couple of colonizers.

5. My first colony fleet only colonizes new systems, gets the first planet up and going fast.

6. My second colony fleet travels to the first established planet in a system, and then proceeds to colonize the other planets in the system, hammering support to one planet until it is profitable before moving to the next planet. Because you colonize from the same system, you give it support every 2 turns. This builds even a very bad planet up fast.

7. I research trading/freighters the 2nd tech in, starting at about 10 turns. Get those freighters up and start cranking them out.

8. I only build stations in one system at a time. My rule being, if I can't build a defense fleet for them, then I won't build them because they are just specter fodder. So that being said, I build up stations in one system at a time for the most part until they have a few improvements done, and when I build them, I also build my defense fleet to protect them.

9. Station build order is very important. When building trading/diplomatic/command stations always build warehouses and docks first so they improve your trade before you have to start paying for the other station expansions. Get the money flowing first. That way it is there to pay for it later.

10. Build your first Police Cutters before your first trading station goes online. Always try to stay ahead of the pirates with good amounts of police cutters to keep them in check.

Using this strategy I have had an empire with full fleets and 48 million bucks in the bank within 200 turns.

What are your starting settings?

I agree with hasoos w/ regards to start up strategies.
I set my opponents to hard; but everything else is on default settings.

*I go for Mat Applications because it reduces costs of stations
*I research X-ray beam bc the freighters are then automatically outfitted with the beams as default weapon; also because I prefer the police cutters to have X-ray beams and would rather not prototype/retrofit police cutters.
*Then I research trading/freighters
*Terraforming improvements
*Asteroid Mining