Gigs are cool. Gigs are lovely things. I've tried to come up with everything that will make your gig experience just that little bit more fun and less stress-free.

BEFORE THE GIG

tickets
x Book about 1-2months in advance. If you intend on going to a lot of tribute gigs, they will be easier to book. By booking early you have a wider choice of seats and also the peace of mind that you're definitely going!
x For bigger gigs, i.e. bigger artists, book as soon as possible. When I saw Paul McCartney a lot of the best seats were sold out in hours.
x Try, if you can, to book the expensive tickets. Again, like the McCartney gig I went to, I booked the cheaper tickets and we were so far away. Gigs like this don't happen that often, so it might be worth splashing out!
clothing

x Take a coat. If it's a gig in a theatre, when you leave it'll be cold (especially if you're in England).

x Take a decent-sized bag. Big enough for purse, camera, keys, drinks, etc.

x Wear shoes that are going to be comfortable. If it's a stand-up gig you don't want to go home with a load of blisters.    
THE GIG

x Get there early. This is especially important if it's a stand up gig 'cos you've got a better chance of getting to the front.

x During intervals, take it in turns to go to the toilet. If you got your place at the front, you don't want to lose it, so get your mate to hold the coats/bags and save your space, then do the same for them.

x Don't buy any merchandise until after the gig. You buy it before, you just got more stuff to keep your eye on.

 THE PERFORMER

x If you want to meet them, either turn up early and catch them taking the guitars in, or wait afterwards at the stage door. They'll probably be happier to stop and talk then, once the gig's over.
x Take a banner. Don't make it too rude or potentially offensive, but then again, make it a bit more originally than "I LOVE JOE" or whatever.

x Take pictures at the right times. Don't take it if the performer happens to be looking in your direction. I always take them either at the end of a song, or during a guitar solo or bit where they aren't at the mic.

x If you were lucky to get to the front, try and make eye contact with one of the group. This way, if you meet 'em afterwards, chances are they'll remember you and give you stuff!

x Throw things: Bits of paper etc. Jelly Babies at Beatle tribute gigs always go down well, but don't throw them AT the performers, just chuck 'em on the stage.

 AFTERWARDS

x Don't forget anything. Check under your seat etc.

x Buy your merchandise, but be quick. There'll no doubt be a queue so work out what you want before you get to the front.

x Steal the posters advertising the gig. They'll be more rare than the posters that were for sale.

x Get food/drink. You'll be hungry.

x Don't miss your train. If you went by train.

x Keep your ticket. You can look back in 90 years and have fond memories.

 DO'S and DONT'S

x DO take a camera. Check first that there aren't any Staff around, or alternatively take a pic when you notice others taking them. The worst thing that could happen is you'll get it confiscated and have to collect it after the show. However.........

x DON'T take your best camera. Try to buy a good quality disposable one. You don't want to drop or spill drink on your best camera. And if you get it confiscated, it ain't no big deal.

x DO take everything you'll need - tickets (duh), camera, money etc
x DON'T take more money than you need. This way, you won't spend it on useless crap like a beer mat with the bands logo on it or whatever.
x DO take a pen for autographs etc.