Prep is the hardest and most expensive out of everything.... I did this on the side a few years ago but it is very hard to make good money and do a good job.
If you have access to a trailer use it,
1.- Strip the FJ down completely on the exterior. Doorhandles, roof rack, mirrors, fender flares, side steps/rails, front bumper/ rear bumper, lights, grill, antenna mount, emblems, any plastic pieces on the body. Hey...you are now half ways there.
2.- now wash the whole vehicle and all the parts intended for paint... with dish heavy dish soap to remove all the wax and grease.
3.- lightly scuff/ sand all parts to be painted. Ensure you DO NOT miss an area, or your new paint may bubble or peal at that area.
4.-now wipe down the whole vehicle with degrease... not simple green, but you must buy this at the paint shop.
5.- Begin to tape off the areas that are not to be painted.. after taping, use paper to cover the rest up....
BTW.... this is only for the exterior, not the door jams.
i wouldn't go for the cheapo option as it will show in a couple years (remember Miracle Auto Painting back in the day?). also, keep in mind that your engine bay and other interior parts are color-matched to your exterior.