Welcome to KH!
My mantra these days is: pick a pattern you love, and all the rest will follow! If you pick something you are absolutely in love with and want to wear really badly, then it'll trump most frustrations.
There are a lot of factors -- how patient you are, how much you love the project, how much you love the yarn, etc. So far I've found that it's true: minus tension issues, if you can knit, purl, and yarnover, you can pretty much make anything. (Tension issues seem to largely work themselves out eventually.)
As others have said, take it slow. Be willing to frog multiple times. See it as a learning experience that has the bonus of not only preparing you for the next project, but also for leaving you with a tangible result: something lovely to wear!
Are you on Ravelry? If you're not, get yourself an invitation now! You can easily browse thousands of patterns there, by level of difficulty if you like. Knitty is a great resource as well.
Hope you have as much of a blast learning knitting as I am!