The best way is to first of all determine your budget then go to a music store to try some out. A good bass for one person may not necessarily be the best option for another. It's a little like trying shoes, you find one that fits you best from a physical standpoint and also from the sound. After trying some out and finding the one that you like best, you can consider looking for that particular bass used on CL, classified or the stores. Buying used basses makes sense if you're careful about it and perhaps go with someone who can identify issues with the bass. Is the neck straight, truss rod maxed out, do the pickups work as they should etc. When you buy a used bass, you will save money on the purchase and also should you want to resell it and move on to another bass, you can sell it for basically the same price you paid for it as it was already used. It provides the least risk involved imo.
Looking at particular styles and brands also depend on the kind of music you play, do you want a Fender-style bass, an active bass or a passive one, the kind of pickups it should have etc. There are a lot of inexpensive basses out there that are great to start off with-
Squier - P bass, Jazz bass, Jaguar bass (Fender style basses)
Sterling - Sub Ray4 (Musicman style bass)
Ibanez - SR300 (slim neck, active bass, solid all-round bass)
and many more.