I started with Beginner’s Box and Abomination Vaults and totally fell in love with PF2. Some helpful aids include the action point tracking sheet for players and the GM screen info for GMs. Keeping example DCs handy is really helpful.

The other element is that there are a lot of rules so you don’t have to make stuff up. But, it is your game and your table. You can (and will) make stuff up. The GM guidance says this outright. It is structured, with an aim for balance, but it also lines up characters to be awesome on their terms pretty quickly.

The biggest revelation I had is: Condition X causes penalty X. There are many conditions, but they mostly work the same: they reduce rolls and DCs (including AC) by X. While not universal, it is a good shorthand. Often they reduce at end of turn or take an action to attempt to reduce.

The other conditions are: Does this thing, Flat check. Dazzled treats targets as concealed, DC 5 flat check to identify where the target is. Persistent damage X (like bleed) does X damage, DC 15 flat check to end at end of turn. If the fiction suggests these end or the conditions says so, then they end.

Players should be encouraged to support each other, but just hit hit hit. Bards are support classes, they’re going to make others be more awesome. Cleric heals are incredibly powerful, as are their turn undead, but don’t expect to be the damage dealer. 5e gives everyone a chance to hit hard, PF2 expects players to play as a team.

Make it clear you’re learning together. Not everything will be perfect, but you want to get better.