For starters: don't get all caught up in SoSuave language mumbo jumbo. All this trying to neg and make her think she's not the prize stuff really reflects more on how you feel about yourself than her. You don't need to take someone else down in order for them to feel insecure enough about themselves to not screw you over - despite the experiences you may have had with women in the past, most women really aren't out to get you. And, most of them already have self-image and self-esteem issues despite the front they may put on. I've dated all types of women, from rail skinny to model looking to overweight chicks, and all of them have this feeling of "I need to fix something about myself" already in their heads.
I say that to say, so long as you're giving off the vibe that you're confident in yourself, that alone will help her see you as a prize to be won, without having to make her feel crummy. With that said: I'm not seeing exactly what damage you need to fix. Again, SoSuave language will have you thinking you failed because you've gone out with her 4 times and haven't had sex. Don't fall for this. The last few girls I dated, I purposefully waited 2 to 4 months to bang them. Remember, as fun as sex is, it's also a bonding act. After having had a few first/second-date hook ups, I realized that some of those girls ended up not being ones I should have bonded with in the first place, or ended up having emotional baggage that I turned a blind eye to so I could score. The main fear most guys on these boards have is that she'll lose interest if you don't give her the D right away - and yet, many of them have stories about sexing the chick they were after but then having her lose interest. In other words, the thing they feared would happened ended up happening anyway.
So, if you've been able to make out with the chick on most of these outings, you're doing fine. And believe me, when she's ready to take that next step she'll let you know in her own way. The most obvious one would be if SHE invites herself over to your place or her place. In fact, these days I always let the girl initiate the whole "apartment visit" thing because, as I always say, if SHE's the one bringing it up, you can't get rejected.
Until then, make her FEEL like you want her for more than that by inviting her out to do stuff. Dinner and a movie is kinda safe but good if you're nervous; also good is comedy clubs - it gets her laughing (which puts her in a good mood) and most places offer drinks. So, you'll have her laughing and drinking, which should loosen her up to want to do other things. Also good: dancing. Salsa dancing is great for seduction; taking her to a night club for dancing allows her to get comfortable with the idea of rubbing up against you; and it's exercise, which will get her endorphins moving.
Lastly - and I can't stress this enough - even though you feel she's a dime, ALWAYS ASSUME THE WOMAN DOES NOT SEE HERSELF THAT WAY. In her head, she's probably a 6 or 7 at best - the goal is to play off how SHE feels about herself, not how you or the world sees her. Plus, once you spend enough time with her she WILL be taken down a few numbers in your scorebook. Once I realized that, at some point, any girl I date will want to have an argument, or emotional issue, or do something that's gross, or do something to annoy me, it made it easier for me to talk to ALL girls because I knew that, while their outer shell may be aesthetically pleasing, you will end up having to deal with some of their bullcrap. This made me look at them like a REAL PERSON with flaws, thus allowing me to talk to and date anyone regardless of their looks.
Hope this helps!