First couple of things.
Your main expenses are:
Army
Forts
Advisers
Navy
Your main incomes are:
Well this is tricky; in general the biggest sources of income are taxation, trade and production, but the amount of each individual income can vary based on context (geographical, political, historical, tech level etc). For example if you are physically located in a place that doesnt have great trade node, your trade income will only get so high no matter what (its basically not worth investing a lot into it, at some points in time at least); if you are located in a great end node (or a node where you can pull in a lot of trade from other nodes) then your trade income might overshadow all other sources of income - combined (Portugal is very capable of that for example).
So depending on your exact context, you should analyze what you have at your disposal and plan how to maximize it. If you have provinces with high base tax (or provinces where you can develop high base tax easily, such as farmlands) then you should build temples there as they give you +40%, so for every base tax you get, you basically get 40% more. Similarly if you have a valuable trade good, where you will build a manufactory, also plan to build a workshop. Stack bonuses that go well together (local tax modifier scales very well with base tax for example).
Now here are some things to consider:
When you start the game, generally (depending on size and context as i said earlier) you wont be making a lot of money. You have a couple of things you can do to improve your economy, but in 1444. only a few are at your disposal. You can develop provinces - which cost you monarch points - and if you do that, you will probably lag behind in technologies and ideas (every few dip/adm tech levels you will get +10% trade/production efficiency, and there are many ideas that give similar boons all over the idea tree). If you lag on technologies, you will also unlock buildings later, and some buildings can literally be game changers (temples and manufactories very much so). And aside from that you can play with advisers - either hire basic advisers of higher level OR use estates to generate 50% cheaper advisers. But as you can guess, if you go for advisers, you wont have enough money to go on early rapid expansion or save up for expensive buildings.
So to summarize:
In 1444. you cant afford everything. If you spread income everywhere equally, you wont be good at anything, and it might take a lot of time to benefit from that approach. Therefor it is in my opinion the best strategy to choose to focus on one thing, and then invest your resources toward that and keep going until you meet your objective. If you go on insane conquest spree literally from day one, it is not very likely that you will be able to maintain high level advisers, because military carries large costs with it (specially while at war when you cant turn the maintenance down). Without advisers, youre not getting maximal monarch points income, and thus you will have less mana to develop provinces. The more you conquer, the more it is likely you will also start lagging behind on ADM tech (as you need a lot of ADM points to core what you conquer). On the other side, if you stay peaceful, keep the maintenance low, and ally someone big (to make sure no one comes for you) you will be able to hire advisers (or save up money) or shift your resources in other ways to maximize the return on investment (build temples in all good provinces for example etc) - but this strategy of building up a powerful base before you start warring also comes at a price - you wont have conquered a lot (or anything at all) for as long as you stay peaceful.
In the end:
In the end i advise you to treat every game as a unique example, as politics and geography make things very different. As Moscovy, for example, i often simple conquer Novgorod and other minors, and then completely chill out for 50 years until i build up economy and ideas, and then simply go on a rampage conquering everything. It is as viable as conquering steppe people from day one imo. There is no "one size fits all" solutions. Try different things, see what works for you.