Here is an article I found, Hope it helps
How to Trim Your Own Hair
http://www.long-healthy-hair-advisor.com/trim-your-own-hair.html
You've decided to take the plunge and learn how to
trim your own hair. Or maybe you're just curious and are wondering if it's something you can do. Or you just wonder how other
people do it. Well, I'm going to share with you some of the various techniques for
trimming your own hair as well as
the method(s) that I currently use on my own hair.
Search and Destroy
This basically trimming individual split ends. It is
a good method to use occasionally when you see split ends here or there.
If you're new to learning how to trim your own hair, this is a good method to start with. It can help you retain length while getting rid of some damaged ends.
It is not a solution if you have severe damage and split ends. If you do too much, you'll just end up with uneven hair. So, it would just be better to go to a salon and have it trimmed evenly.
The simplest way to do this is in front of the mirror in the bathroom. If your hair is dark and the
bathroom counter is light, it will be easy to see the split ends.
Take a
pair of scissors specifically for hair trimming (not the old scissors in a drawer for cutting open packages!) and snip of the hair just above the split end. It can get tiring so maybe just do one section a day. This is not a fix, just a way of getting rid of any spare
split ends.
This method is sometimes referred to as dusting because when you are done, you will see a "dusting" of hair lying on the counter.
Twist and Snip
A good way to find split ends that need to be cut is to take a section of hair and twist it. The hairs that stick out are most likely split ends. (If your hair is in layers you will find this not to be true.) Some people just cut all of the hairs that stick out without looking to see if they are true split ends. My suggestion is to still look at the hairs and determine if there are split ends. Then cut them individually. Cutting all the hairs that stick out is a really bad idea because it could thin out your ends if you do this too often.
Have curly or natural hair? Click here to read my article on natural hair trimming.
Dusting
Dusting your hair is a trim of 1/4 and inch or less. This method is also referred to as dusting because even though your hair is being trimmed evenly, it is so little hair, that it just looks like dust on the
floor. Getting to where you only need this type of trim is a good goal to shoot for but don't put yourself there before you are ready! This method to trim your own hair should be combined with the ponytail and scrunchy method below.
Ponytail Method
An easy way to trim your own hair is the ponytail method. The ponytail method is pretty simple in that it just means to take your hair and put it in a ponytail. Then you cut off the desired amount of hair. If you do a low ponytail, you'll end up with even blunt hair. If you do a high ponytail, you'll end up with subtle layers. If your hair is shorter in the front, this method may have to be combined with other methods.
Scrunchy Method
The scrunchy method is just another version of the ponytail method but I think it's the easiest way to trim your own hair. It is taken from the method that
Feye describes on her web site where you put your hair in a low ponytail with a scrunchy and pull the scrunchy down to the desired length that you wish to trim off before trimming. The scrunchy acts as a guide.
View Feye's tutorial for pictures of her trimming methods. I have been using Feye's trimming methods for my own hair for the past 2 years and they work very well. You can vary and adjust it for your own hair's needs. For example, sometimes I do a tiny dusting layer by layer to make sure I'm not missing any splits before I proceed to the ponytail scrunchy method.
Conclusion
The biggest piece of advice I can give you in learning how to your own hair is to
only trim off a little at a time until you are more comfortable with it. You can always go back to trim more if you need to.
Additionally, do not become scissor-happy with your own hair. I have a habit of trimming one month and instead of waiting for my two month time table, I'll trim again the next month because I see split ends. The truth is that it's practically impossible to eliminate every split end on your head. There's no need to be manic about split ends. If you couldn't trim your own hair, you'd wait that two months, right? So, determine a trimming schedule and stick to it.
Looking for more details on how to cut your hair professionally?
Learn how to cut layers, bangs, and other cuts.