In a nutshell, the process involves trimming all your hair to one length, and then cutting down the sides and back further to get a tapered, neat appearance.
However, cutting hair by yourself is still a somewhat tricky procedure. If you haven't done it before, it could very well lead to disaster, so don't do this the day before your big job interview. That said, it gets much easier with repeated practice. It'll probably take 20-30 minutes to cut your hair, especially if you've never used clippers before. So take your time, you'd spend even more time at the barber's, and, if you like to maintain a clean-cut appearance, the $10 you spend on clippers will pay for itself dozens of times over.
Besides, hair grows. Right?
Step 1: Supplies
These are going to be the most important part of your operation. Pictured are a set of Wahl clippers, which are popular since they're usually the cheapest out there. If you buy clippers, make sure they come with a good assortment of blade guards.
Second most important. Usually they come numbered, although many will also be color-coded and/or have actual length measurements on them. If not, as I understand, the numbers are increments of 1/8", so a #8 blade guard will be an inch.
You're going to use this to look at parts of your head other than the front, in tandem with the big mirror. I stepped on mine this afternoon, cracking it. Yours should not be cracked; it makes this really hard (and kinda dangerous!)
This, with the hand mirror, will give you just about all the views you'll need of your head. Make sure this one is big, and mounted to the wall, since you can't hold two mirrors and a set of clippers.
This is where you're going to put the hair you cut. You're going to want it right there, if possible, so you can just cut your hair and let it fall straight in there.
This is a good thing to have, too, since otherwise you'll have to sweep up frustratingly small bits of hair off your floor. This is just a shopping bag cut open.