#2: Read lots!
Read lots and lots. Read Autobiographies by other entrepreneurs who gave it a go. This helps your in untold ways (depending on your situation) – lessons, frames of reference, new perspectives.
#3: Tighten your belt
Whatever you were earning before, prepare to live on 1/3 of it. And prepare to do for 6-9 months. I know you think it sounds drastic, but ask anyone who has done this it sounds realistic. (You will be surprised at how much income you wasted before!)
#4: When do you quit? (your current job)
If possible get a fixed contract to go off (before you quit), this will help ease you into the process. If you are the kind of person to procrastinate forever quit your job to put yourself in the deep end, in order to get you started faster.