If you are going to start a major collection:
Check around for what product line you like -
Nikon, Minolta, Cannon are the most common (i.e. have tons of glass available). Basically, you are choosing your lens mount at this point.
For me, autofocus is non-negotiable - the Maxxum was the first effective a/f body, so that’s what I’ve got.
There are lots of older bodies to accept any given line of lenses - you can always upgrade bodies relatively painlessly - just make sure you won’t out-grow the glass.
Recap:
The body must have:
Flash shoe
tripod mount
cable release
Eventually, you’ll want more lenses:
wide angle
at least 200mm telephoto
macro (everybody loves macro)
Cannon/Maxxum (Dynax in Europe)/Nikon all have a variety of these.
If you foresee wanting a truely unusual lens (1000mm? Cannon makes one) (Macro zoom? Maxxum), find out if such a lens is made.
Newer bodies have some neat bells & whistles (flash on second curtain, built-in auto-metered fill flash, predictive a/f) but, unless you see an immediate need, don’t pay the premium price.
Also avoid power zoom lenses, but that’s more of a pet peeve of mine.
Recommendation: find a body that’s about 3-5 years old, with a twenty-something-to-80-something zoom that CAN do auto-everything, but can be put in semi-manual or full-manual mode - there’s nothing wrong with using the same gear to do snapshots and real photos.
I generally shoot aperature-priority - I know what depth of field I want, and let it figure out shutter speed. (When in low-light, use ap. priority, just set the ap. wide open).
Good Luck!
(p.s. - I love photo.net, too)