I've given myself quite a few trims and i'm much happier with my own results than i have been going to salons!

I've tried a number of methods, cutting one curl at a time worked fine, you can also add layers by damping/wetting hair and combing it as straight as possible, then tie it up in a scrunchy right at the top of your head and then pull the scrunchie till its almost all the way out and snip the end off (you might want to do all this with your head upside-down).

If your hair is longer you might also want to try Feyes instructions, you can get a v or u shape using her directions, v shape looks great on long curly hair