Mornig geeza.
The best way to prep a painted frame is to:
1. Have it sand blasted.
2. Use a paint strippin product,prefrebly nitromors.
Option one is obviosly the easier road to go down,but if like me you like to get involved and get your hands dirty strip it yourself.It took me a couple of weeks to strip my TA in between doing my day job.You would also need some wet and dry 240 up to 800 ish and some scotch pads.Another tip if you do use the nitro is when your doing the hards bits (welds etc) apply the gear then cover with foil so its as air tight as possable and leave for 20 mins or so.It makes stripin those hard bits so much easier.
F*ckin hell it sound like a bloody delia smith recipy!!
Good luck.
SI.