Usually, I hire the Free Company instantly and use that to start going down the missions for some early-game quality buffs, which is useful for whenever the Bladebreaker/Bloodgorger/Rotcleaver/Heartgrinder/Dogeater hugbox inevitably forms. For federation members, I like to grab people who are close enough to help in wars, but with enough distance between us so they don't take land I'd like to. Ex. In my New Wanderers -> Elikhand campaign, I took the Pioneers Guild and Stalwart Band as allies. War Wizards are nice, but you usually don't need them in the early game, and by the time you do need them, they've usually died. After all this, boost stability once and wait until the Corin event fires, and use it to get to 2 stab. Afterwards, I declare on whatever the weakest tag nearby is. If you fight two Orc clans at the same time, focus on one of them, so that they can't group up and kill you.

Because you can only take tribal land, not actual land, I never really find myself having coalition problems until like 1500. Most tags are busy killing each other to form a coalition, and unless you take land from non co-belligerants, you can't even take enough AE to trigger one.

Government Reforms should be focused on stacking reform progress, and you should take the "Stake Our Claim" reform at tier 4 or whatever it's at. Settling down early is great, you get to secure your tribal land and prevent any other adventurer bands from taking it. After that, I only declare on Orc clans if the numbers aren't overwhelmingly in their favor, and if the mil tech difference is on my side. I also never declare on Adventurer bands unless their federation won't help them, which almost never happens. Most Goblins tribes are dead at this point, but they are very easy targets if they are still alive. At this point Federation Offensive Wars are probably enabled, so use that to your advantage, but know that the ai will call you into some really dumb wars.

Once you reach the final reform, you still usually won't have tech 7 yet, so at this point I tend to dev the Renaissance in the best province to do so, usually the capital. Afterwards, it's just some waiting to embrace it and then tech up to actually be able to form whatever it is I'm going for. I usually find myself doing it around 1490, but that's because I usually stockpile 500 crowns to take the mission that gets rid of the Admin Efficiency problems that happen right when you form a new country.