Well, may as well toss my hat into the ring.
I've been a bard in various LARPs over the years. Lived in Sweden for three years, then moved on over to the US around 2007 and have been here ever since. Spent a lot of free time LARPing, which has been a great distraction from everything in life.
Now, for all you aspiring bards out there, here are a few simple tips to get you going:
1) If you are not entirely sure how to tune your instrument or sing, please do not bring it. If you play for comedy, that's fine, but people can get fed up really quickly, and a shitty bard will die faster than you can say "titty-fuck".
2) Learn to disguise the modern aspects of your instrument. If you're a guitar player, Martin makes a wonderful backpack guitar that is sturdy as fuck, cheap as fuck, and easily modifiable to look like a 'fantasy' instrument.
3) Learn how to sing. Even if it's poor. Simple instrumentals bore people quickly unless you are very, very good.
4) Learn how to make up songs. If you're playing a guitar/mandolin/lute, have several good-sounding chord progressions you can sing over. Relate songs to people. If you're playing a melody-line instrument, then know how to improvise something catchy and folksy
5) Do not bring your best instrument with you. It will get ruined somehow. Watching a guy cry over his 700$ is hilarious only when you're not the one holding it.
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.
13) If you're getting tired or can't keep playing up to your normal level, stash the instrument and go questing. If you're not at your best, you're not helping yourself by forcing yourself to continue. You're here for fun, after all.
14) If you can, bring a few instruments with you. My usual 'weekend kit' consisted of a bodhran, a well-disguised Martin backpacker, a couple willow flutes, and my nyckelharpa (which violates rule 5, but I help build the fucking things, so I get a pass). If someone knows how to play, loan stuff out. Teach people some basics if you feel like it. Charge a bit, and enrich the world.
15) If you have to do some metal, stick to less well-known stuff. Everyone knows Blind Guardian. No one expects to hear you jam through Pixie's Dance into Juokse Sina Humma into Ett Norrskensdad. Bonus points if you know some good theory
16) Gain patronage by writing songs for nobles. This will improve your survivability.
17) Learn how to drop your instrument and pick up a weapon in one smooth motion. Some instruments make this easy; other instruments don't. Learn exactly how long it takes you to be able to defend yourself. This relates to rule 5, as a shitty, replacable instrument is easier to just drop
18) Seriously, stop playing "The Bard's Song". I swear I will slash your goddamn tires
19) Teach people songs. Nothing makes friends like teaching someone a quick drinking song.
20) Have fun. It's what you paid for. Be flamboyant, be a bard, and be awesome.