I've been cutting my own hair for nearly 15 years. I cut my daughter's hair as well.
At first I started cutting my hair because I figured I could create the same mess for free that every stylist made of my hair for loads of money. One stylist "ruined" my wedding "look"...in February 1998. I looked like Art Garfunkel's long-lost twin, only about 12 years old, and female. (I was 32). In addition to the overly short, completely unmanageable hair, this same stylist decided to "brighten" my color with a "highlighter". My hair was purple. I'd been going to the stylist for years, but after this last straw, I figured she hated my guts, and I started cutting my own hair, and I color my own hair to cover grays.
A few years after I got married I accidentally ran into my old hair stylist in Target or some place like that. Her naturally red hair had a sort of creepy "violet" tinge to it, and she was wearing it very short. I felt a little better, because that was proof she wasn't really trying to ruin my wedding.
Do invest in at least one "good" pair of scissors. In frustration I have resorted to sewing scissors and my husband's nose hair grooming scissors, and I don't recommend either. Sally's has some decent trimming shears that are cheap. Since you're only cutting your own hair, you won't have to worry about them wearing out quickly.