To prevent obsession, you should start with an initial budget (e.g. 50$) and never pay more. Force yourself to get more money from the tables. Also restrict your maximum buy-in to something like 1/25 of you budget. For 50$, this means tables with 2$ buy-in. The buy-in restriction keeps you at a comfortable level, because tables with higher buy-ins have better players.

Using this strategy I played from 50$ up to 300$ over a year or something. At that point I quit, because I got bored.