I suggest you get a pair of boxing gloves on the cheap (probably around $15 if your American)
Then if you have a pillar or anything that resembles a punching bag (you won't be able to practise uppercuts/hooks on this) and stand in an orthadox stance to it, and just hit it.. you won't have any technique but you will get comfortable with just punching in general, move into the punches using the swing of your body to get weight behind it, i suggest checking these out:
http://www.youtube.com/user/Dennythetrainer#p/u/33/eBhan6SIU5ghttp://www.youtube.com/user/Dennythetrainer#p/u/32/1wD1ZCE2aOYhttp://www.youtube.com/user/Dennythetrainer#p/u/30/ilhZdJHt9CUhttp://www.youtube.com/user/Dennythetrainer#p/u/29/PO4oa6DbrI8It's all very basic and you need to pracise to get the feel for it obviously, and don't worry about getting hit in a fight, adreneline will kick in and you will hardly feel it, the thought of getting hit is worse than actually getting hit!
I box, but try to avoid any physical confrontation
Inb4 SWEET_TOOTH gives you a lesson on streetfighting while adding anecdotes of how absolutely indestructable he is

Fuck a sig, i go accapella.