if you go to school (one of the best places to get sources) then thats your best bet for one. look for people that look like they smoke, they HAVE to get their weed somewhere. just hang with them and youll find sources.
when first smoking, make sure you have someone with you, (preferably an experienced smoker, or someone sober) because, some people flip out and start trippin balls, (i dont know if you will) but just in case, its good to have someone to make sure you dont do anything stupid.
make sure you have food/something to drink. cotton mouth sucks like a bitch.
heres a good one: remember to breathe when spacing off o.O xD
if you want some more tips pm meh, but those are the basis. ^^