I'm another Vicky 1 vet, but couldn't really get into Vicky 2 until recently, when HoD dropped. (Wasn't finding it as interesting as Vicky 1 before HoD.)
The new wiki is a good place to start for sure if you haven't checked it out. (That's probably where you saw the New Players Guide though, eh?)
In addition to the advice so far on Admin. Efficiency, and Literacy, I'd recommend familiarizing yourself with the changes to the CB system from the start. There's definitely a variety of new CB's that you'll actually want to use, and the current system of having to spend time generating a CB in advance along with infamy (BB) has to always be kept in mind. In the latest version, you'll want to understand Ticking Warscore (i.e. can now occupy/defend target provinces alone and still achieve 100% warscore over time...) and how Adding Wargoals works (requires a decent score in relation to military policy to start; resets warscore to 0 in a defensive war, to the required warscore value of the original target, etc...).
I wouldn't run from Influence either; just keep in mind that the second you become a Great Power, you want to remember to set your priorities on the Diplomacy screen and start influencing someone so that you're not wasting points. (Colonial Points in HoD should receive the same treatment.) So, yeah, accumulate some points, read up on the tooltips for the actions they let you take and play around sphering who you can, I say.
Really, there's more great changes that I would go into detail about that were introduced with HoD and the latest beta patch, but I presume from your icon that you're just working with Vanilla Victoria 2?
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Of course I've got a question of my own that fits the scope of this topic too: Is there any truly effective way (be it gamey or whatnot) to really explode in terms of immigration like you could in Vicky 1 and elevate a South American underdog to potential GP status? Uruguay was great for this before with its Full Citizenship party—you just had to focus on passing social reforms early you were set.
Can you even do anything like this to guarantee heavy immigration to your banana republic in the current version? I don't even see social reforms or immigration policy listed in the wiki as affecting your pull on immigrants....