To prep, what sequence to take?

I plan to sand my ride very shortly. I have been planning this for several weeks now. But I must know one thing. What is the sanding process? what sandpaper do you suggest I use. I do have places that have body work. Shaved handles tails int.... I thought about using 250 then high build and ( wet sand 300) then base and clear.... I also must ask. do I have to use block sanding techiques? I have an orbit sander that works great and I was wondering if I could use this. At least to break down the top coat as close to the metal as i can get. throw some primer and same process with lighter paper and then tack and wack?