It gets women who are not looking for the same thing cancel themselves out.  Much easier.

I agree with Netnoy.  In my profile under "I'm Looking For"  I say:  "You are slim or height/weight proportional."  This is very helpful in cutting down the number of unsolicited contacts I receive from overweight girls I am not interested in.   Of course, I have other criteria regarding their looks, but those I keep private and apply on a one on one basis when browsing.

Be careful how you define your preferences. If you come off implying you will pay for hotter babes, you may run into the site's P4P alerts.  

 
My suggestion: Text and experiment. Try different approaches, perhaps for two-weeks at a time. See which tends to develop the best results.  

 
Netnoty's approach not withstanding (which works for him, no doubt!), you may end up turning away someone who meets your preference but doesn't use the same terms you use. For example, I've seen many, many profiles where the POT described herself as "curvy" when she's skinny and has big jugs, right next to POT's who use "curvy" when they are just fat. That's part of the reason that Seeking eliminated "body type" and replaced it with "weight" ranges. The jury is still out on this change, as many of the profiles, especially those over 6 moths old and those of the "bigger girls" do not include a weight range value.  Anecdotally, the percent of bigger gals in my search results is much higher now than it was before this change since so many profiles are missing this item. So my search process takes even more time now as I need to manually filter out the chubbys. An example of the Law of Unintended Consequences.  

 
Next, in my experience, many POT's (what percent? Maybe 20-40%) will never really read your text or will ignore it.  That may mean a catfish or scammer, or another desperate POT from South America. But it also could mean she just decided to go for it.   For me, I certainly have a specific look I want. But I since I prefer to wait for a POT to message me first, I just do my "looks" filtering when they Favorite or message me.  

Life is good

 
The Cat