6) Keep your social skills up. You are meant to entertain and keep people motivated. If you are sitting around playing an instrument all the time, that will not happen. Schmooze, hit the bar, or even go adventuring. Here is where your singing will come into play; if you are good at making up songs, you can do cool things
7) Have a good repertoire BEFORE you show up. Constantly repeating yourself gets old fast, and you'll piss people off if you keep playing the same thing. Make sure to have variety; a good mix of folk from a variety of cultures is good. People love Irish songs
8) Learn a few simple marching songs. "Regin Smiður" is my personal favorite; teach your party the chorus, and then march for hours as you go through the 130 verses in Faroese.
9) Have some showmanship. Whether it's flashy entrances, a cool hat, or being able to dance along to your own music, people will like it more if you're engaging. On that note, know a few Irish drinking songs. People love them, and they're easy to stomp along with
10) Sitting around noodling might be fun, but it doesn't really draw an audience, and trying to play overly-technical stuff can turn people off, especially if you keep making mistakes. Good fiddle players are exempt; nobody loves anything more than a retarded good fiddler going to town
11) For the love of Christ, STOP PLAYING 'FOLKSY' COVERS OF METAL! I know you love Blind Guardian, but if I hear "The Bard's Song" one more time from an inexpertly-played, poorly sung pawn shop acoustic, I will fucking knife someone. You can throw it in occasionally, but making it all you play is incredibly annoying and throws people out of the experience
12) Toss a hat down for some in-game currency. Adds to the experience, and maybe you'll get lucky and gain patronage. It also gives thieves something to do.