What you like vs. What you dislike

In general, most people are far more shallow about their "Pros" lists than about "Cons".

That is, in a "Pro" list they put down things like "Must be 6'+ tall" or "Must have big breasts".

But for their "Con" lists, they put down things like "No drug addicts", or "No unemployed".

This is a mental trick actually.   In both cases, you are thinking of extremes.   When you think Pro, you think of the best, so you put down a description of something that is actually a bit better than you really truly need.  When you think Con, you think worst and you put down something worse than what you really accept. .

For example, when talking about employment, a Pro list might include "CEO", while a Con list might be unemployed.   Honestly, if someone was second in command to the CEO, you probably would take that and similarly, if someone was working at McDonalds, you probably would not accept them.

This is one of the major reasons I much prefer the Con list to the Pro list.   If you truly want to be less shallow, stop thinking about what you want and think about the things you can't accept.

Your list will be morally superior, and honestly you will meet more people and BETTER people. While being shallow is OK, being deep has advantages.

Another good reason to use the Con list then the pro list technique is that you are less likely to be in a situation where you fall for a total douche.   When you use the pro list, you go out with people because of things, then slowly find out their problems and eventually decide not to date them.

When you use the con list, you go out with people because they aren't a douche, then slowly find out if you really like them.  Trust me, it's a lot easier to stop dating someone because you don't lust after them than it is to stop dating someone that you lust after, but is cheating on you.

Now, this is just a guideline, there are exceptions.  It is possible to be shallow on the "con" list too.  Some will say "No short men" or "No woman that ever so much as wanted children - even if they don't want them now".  

But moving to a mostly "con" list is better than sticking to a long "pro" list.