the 'buffer' you have... is it a proper polishing machine or one of those £40 jobbies from halfords?
as you car is black you could try poorboys 'black hole' - that polishes nicely and contains fillers too
as for trim... tape it using 3M trim tape before you start polishing... saves a lot of time afterwards
for trim see the sticky section for help and advice... it is the holy grail to find an definitive answer!!
what dragonfly said was the correct order - although I would pop in a quick wash after the claying to removed residue
do the glass last
for interior, if you can, get yourself a decent degreaser/APC they really do the business for lots of jobs