At the risk of creating another post about this that folks will not search to find. What's best for Paul is not best for Peter. If you are talking DIY with "normal" tools, Angle grinder is too aggressive unless a "cleaning disc" is used. Sort of a scotch brite on a wheel. (hook and loop stuff). There are many other ways. All have their pros and cons. Chemical=messy/leaves residue(chemical creep after paint). Blasting=need equipment/walnut shells/soda. You can warp and ruin a truck with blasting. DA= good. Hand sand=good/takes forever.
You DO NOT have to sand to bare metal if underlying paint is good and you are not changing color radically.
The best for DIY is DA. The best for overall, cons vs pro, if done by professional, is Soda or glass or plastic. Whatever you do, if you take it to bare metal, you have to prime/protect ASAP!!!!
