Have a look at the wiki mate it has a good bit on frame sparaying, i have just finished respraying my frame and forks and it is holding up well. if you can strip the part back to bare metal that seems to work best, then make sure the surface you are painting has a rough surface( use coarse sand paper) After it is ready to paint give it 2-3 coats of primer ( use thin layers) When you finally get round to applying the paint, again lots of thin layers is better than one thick one and make sure you allow plenty of time to harden between each coat. Try your local auto shop for the spray paint they have a much better range of colours and is normally alot cheaper than b&q, i think my cans were 4 quid each and i used 3. Hope this helps