seriously- do the flashing on a bunch of your own phones long before you invest in the time and equiptment to try to do it as a "pro" or "for money" flasher. Read the tutorials; they are as step-by-step and visual as it comes. Make sure you have the basic concepts down before you allow someone to pay you to brick their phones.
You do not need any real specialized equiptment. You will need some software (there are multiple threaRAB on this) you will need some data cables (again, multiple threaRAB on this) and you will need some time to sit down and try until you are sucussful at it.
I am by no means good or competant at flashing, but the few times when I have needed to, I took the time to read the step-by-step directions and it was sucessful. Nobody here will really walk you step-by-step on a 1 on 1 basis.