If you're new, do not buy used machinery
If you're new don't buy junk (new or used).
My first mill/lathe was one of those Chinese 3 in 1 machines, not good at doing anything really and I never quite figured out what the third function was....
Soon afterwards I bought a used Seneca Falls Star lathe for $300 and still have it today, was happy to sell the 3 in 1 for only a few hundred less than I paid. It only takes a little searching on this and other sites to see that people have trouble with both new and used machine tools.
A lot has to do with how mechanically inclined you are, if you're the kind of person who rebuilds your own car engines then taking on a project machine might be just the thing. If however you have trouble installing a new garbage disposal under your sink I would definitely recommend buying new from a company that stands behind their products.
Precision Matthews is a sponsor on this forum and lots of folks are happy with their machines. Mickri has the right idea with putting together a list of what your needs are and shopping based on that. However, if you can pick something up for a few hundred bucks like I did you're probably not going to be hurt from the experience even if you end up selling it later.
If you're doing this as a hobby then you can expect to learn things later that you wished you had known up front. The best machine is always going to be the one in your shop that gets used regularly, big or small, new or used, if you can do the work you are trying to get done it really doesn't matter. Heck, we even have members forging metal in coffee cans and cutting steel with chisels
Coming on here and asking is a great first step. See if there's someone in your area who will invite you into their shop and show you around. Take some adult ed classes if they're offered near you or visit a makerspace if that's an option. Like I said this morning, read and ask questions. There's lots of help out there if you're open to it.
Cheers,
John