Well, you ask difficult questions, in a sense. I'd start with one of
the "Big Box" stores like Lowes or Home Depot, and see if they have
any literature. You also might get some help from a friend who has
done a lot of painting before. Cook them dinner. Always works.
A 3 step stool/ladder does wonders for the hight issue. I am 5'11",
but with the 8 1/2 foot ceilings in my current house, I need a bit of
help. A 6' step ladder is also good. You should have one around
Prep is everything. Scrape/sand any loose paint, spackle, etc. The
surface MUST be clean and smooth. Check out surface prep material like
TSP - tri sodium phosphate to remove any traces of grime, grease, etc.
You can't paint over grease. This is an especial problem in kitchen
areas from cooking fumes.
Consider "eggshell" finish, versus flat paint for areas like
bathrooms, or kitchens. Easier to keep clean. However, it doesn't
cover as well, so you might need more coats.
If you are doing the same color, then 2 coats usually does the trick.
If changing color, look into primers like Kilz or Zar. You can also
get the primers tinted to the final coat color, which helps a lot. I
did pink over green one time in a bedroom, and it was a non-trivial
Metal -- same deal, prep, etc. You often get better adhesion with a
oil based paint. Also check out "liquid sandpaper," which is a solvent
surface prep material that is good for surfaces that have been painted
with an oil base paint.
Don't skimp on paint or brush quality. Blue "Painter's tape" and drop
cloths are your friends.