Its always good to know how to trim your bangs! Most women have experimented on cutting their own hair anyway. The longer I worked at a busy salon, the more it became evident that women are going to cut their own bangs in between visits to the salon. I finally gave up asking them not to do it, and started teaching them how to do it instead. It really helped both of us in the long run!
Its really important for women to take control of their own lives, when and where they can! Making hair mistakes is only part of the learning curve. The more mistakes you make, the more you know what not to do!
When you trim your bangs, you should only take a small section of your hair. The finished section will look like an upside down V. Part your hair down the middle with a rat-tail comb, and then you will make two more parts. Start the second part from the center part around the front of the ear. (Draw a mental line from your ear to your center part.) Part from the center part to where your eyebrow ends on one side, then part it off the same way on the other side. This is the section you'll use.
This image should give you a better idea about how to cut your own bangs or at least the section you should use. The image IMHO showed too much hair for a bang section. I used my photo shop to draw my own line in pink. (sorry the lines aren't perfect.) This is all the hair you should need for your bangs, and this is how we were taught to cut bangs in Cosmetology school.
Most women like their bangs to fall just above their eyebrows. Using the bony bridge of your nose as your guide, make a blunt cut straight across. Start with one small section and use that cut as your guide to cut your bangs. Don't make your bangs too short though, unless you want them short. If you are cutting wet hair, you must take hair shrinkage into account.!
Of course, there are lots more tips, so lets get to them!