My nutshell advice:
1. Cheap. On price, not quality. Find used, refurbished, or last year’s model. Buying new isn’t really worth it at the very beginning. But, make sure that any investment in a machine is worth it by taking it for a test drive. Taking your own needle, thread & fabric scrap to see a craigslist machine is totally worth it if it turns out to be a lemon. Don’t forget to read the reviews and compare prices. Amazon.com is an excellent source for consumer reviews, even if you’re not purchasing online.
2. Basics. Unless embroidery and quilting are your main prerogatives when hunting for a machine, you will generally only need a zigzag machine with a needle that can move left, right and center; controls for adjusting both the length and width separately; a free arm; and a bright lamp.
3. Vintage or New? This is a very common debate, from beginner to pro. In my opinion, it doesn’t matter to anyone but the user. Whatever you feel most comfortable with is the right choice for you. Also, I have found that there are machines on the Naughty List that work wonderfully for some people and machines on the Nice List that some people hate to work with.
In summary: No one’s opinion matters as much as yours and, like your first car, you’ll often learn more from a beater than a brand new BMW.