What is the best way to thank your GM?
Be a good player. Show up on time, shut off the electronics at the table, and pay attention. In combat, be ready when your turn comes around so you aren’t slowing things down. Your GM puts in a bunch of work behind the scenes which you will never see. Thank them with your attention and good behavior.
But I’ll also accept an ice-cold Crabbie’s ginger beer or three.
Which RPG provides the most useful resources?
Pathfinder RPG, just by sheer volume of useful sourcebooks and gaming material. If I wanted to start another Pathfinder campaign, I’d be literally spoiled for choice because I’d have a sourcebook and probably an adventure path to support me where ever I set the campaign in Golarion. Heck, I could start the campaign on another planet in the solar system and be okay, because there’s a sourcebook for that. And that doesn’t include the very useful flip-mats, magnetic combat pad, miniatures (paper and plastic), and the many other support products they have available. You could start a Pathfinder campaign with very little advance preparation, and that can be a godsend for the busy GM.
What are your essential tools for good gaming?
Having just said how much I love the many tools available from Paizo for gaming, I’m not going to back-track a bit and say: nothing. There is no piece of equipment, really, that I absolutely must have in order to run a game. Obviously, if I’m just playing then I need whatever the system requires me to have to play. But if I’m GMing, I can do that with nothing more than paper and a pencil (I don’t include those as tools, because I have them around all the time, even when I’m not gaming). I can ask a few questions to get an idea of what the players want to play, a few more to get an idea of the setting and tone they want, and we can go.
Flipping the question a bit, and assuming I’m already in a campaign for something, then my answer is also: player buy-in. I’m willing to tweak things to better fit my players and their characters, but I need my players to trust me and buy-in to the world I’m creating. If I don’t have that then the game isn’t going to be fun for any of us, and I’d rather just play a boardgame.