What size needles are you using? I'll look up the pattern I used later - on our way out. But I used a 48 cast on with size 4 or maybe 6 needles once and they were fine, but kind of a bit loose. Then I made them with size 2 needles - same yarn and they were nice snuggy perfect socks. The one in the pic is on a size 2 - again same yarn, but gotta find the pattern. It was a short row heel and I think I liked doing the gusset ones better.
Good luck and take a pic! These were my first socks I'll attach, and they fit, but were a little looser. And as always with mine, there's mistakes! You'll learn a lot doing your first pair.
Found the pattern for the short row ones: http://www.knitlist.com/2002/ToeUpSock.htm but again, I liked the regular pattern with gussets better.