I'm bad at this game.
I start as Leinster(?), South Ireland. I "immediately" forge a claim on the province to the west, of which I forgot the name and take it by force. This usually goes smooth (I've already tried that scenario 3 times now). So now I have 2 provinces. However, once I try to take Connacht to the north I run into problems. Scottland or England gets involved and they just crush me. I then pay back all the loans I had to take for the next ~10 years and try again, but then they're allied with some other large nation which just proceeds to block my ports, so I run out of funds etc etc they crush me etc etc and I just lose.
I'm basically a noob at this game, having never played EU3. I have played CK2 tho and created Ireland there successfully. I just can't seem to do it in this game, any tips?
In CK2 you can survive as a small nation by being vassalized. In EU3 though vassalization is rare and boring. In general if you get beat by a larger nation, you just lose. People who play tiny nations tend to use exploits, luck (AKA savescumming) and be really, really good at the game.
If you really want to play as a tiny Irish nation, your best bet is to use coalitions and (if you can somehow manage it) an alliance with a large power to keep England and Scotland at bay. One thing you might consider trying is finding a medium sized nation that's allied with France and then allying that nation, because they might call in France into any wars you get into. Then wait until you're confident that England and Scotland are busy, either because they're losing a war, or they're already at war with you and you have a big ally backing you, and use that time to take out your Irish neighbors. Once you unify Ireland... I don't know where you would go from there. Just try to survive against England and Scotland I guess, and maybe play the colonial game?
Honestly though, without both luck and skill you'll be crushed. I would recommend playing as a large or medium nation that has the potential to form a larger nation, like Castile to form Spain, or Muscovy to form Russia. These nations are typically balanced so that they're at least a decent match for their neighbors, and they give you an obvious goal and a powerful nation once you achieve that goal.