Not enough carbonation in my beer

Am pretty new to home brewing and have run into the problem of not having much carbonation in my beer. It tastes Good, but a tad flat; and the head in the beer is basically non-existent. One of the batches I made was from a kit, the other two were recipes I found on home brew talk. I used an 8oz (or whatever amount that comes in the individual packets of priming sugar) but I have had this problem with each batch. After bottling I let the beer sit in 70 degrees for two weeks, is there anything else I can do to fix this issue?

Revvy has a much longer post that may make it here soon, but in general:

Just give it more time. As long as you used the right amount of sugar, it will carbonate given enough time. Some beers take 3 weeks, some take 3 months...just be patient!

I have found that the longer that I let bottled beer sit the better it carbonates. I made a raspberry wheat on April 1st and it is now fully carbonated. I think patience is the hardest part of brewing. I just recently (this week) started kegging my beer with Tap a draft and love that it is carbonated in only one week and it taste great. Happy brewing.

3-6 week (duck an run........... Revvy is comming!!!!!)

Either you didn't wait long enough or you had a lot more volume than normal. Wait a few more weeks. The beer will be better for it anyway.