In general, what you do to get the girl is what you do to keep the girl. But there are some differences. As always, you should decide first what do you want with that girl and based on that you will set your frame. For example, if you just want fun or NSA, you can consider these short term. So who really cares? You have some fun and you move on.
On the other hand, if you aim for long term relationship you might want to pre-think your LONG term frame. Some points that should be considered:
* You want her to respect you (as a man). As long as she is respecting you she remains at least somehow attracted. She cannot be attracted to you if you let her disrespect you. The moment she starts disrespecting you you lost your value and her disrespect will easily change into snowball effect. Once you lose value in her eyes, once she loses interest in you, it is very difficult to get it back... perhaps even impossible...
How will she respect you? At least for the beginning (before the relationship becomes more fluent), make some rules and keep them. It probably sound silly but it is important. She needs to know that you have some solid frame, and rules will simply create this frame. Lifting weights 3 times per week? Good, keep that schedule. She has to wait until you finish. Seeing friends once a week? Keep it that way, no matter what she "needs" you to do on that day.
Tell her that you don't want her to go out with other men and that you want sex at least once a week (and that she can't communicate with her ex). There are of course different ways to tell her that, perhaps the best are indirect ways. One of those indirect but good ways is to start conversation about other people, friends. So you tell her: I have a friend, he has a GF and he doesn't want her to go out with another guys. He wants to have sex with her at least once a week. Then you ask her: What would you recommend to my friend that he tells his GF? Now you involved your girl in decision making, ideally she will tell you how the guy should approach. You can also ask her further questions what she thinks about it, and she will usually give you her opinion about what she really thinks about relationships, including yours....
Set firm boundaries and keep them. Similarly as above, make sure that she knows what you expect from the relationship. E.g. you expect her not to contact her BF, and she needs to know it. She needs to be clear about it, she needs to know that this is what you want. If she respects you she will not contact her ex. If she contacts him regardless what you told her, she is disrespecting you. Beware of snowball efect because if you don't put up clear boundaries and making it clear that this behavior is NOT OK at all, she will keep disrespecting you. Snowball effect can be very fast, even after years of good relationships you could be gone within couple of weeks, if not days. As you know, ideally you would give her a boot for disrespecting you and focus on another girls, but it is your relationship...
* Communication. You don't have to talk like a girl all day long, but you should communicate. People change over time, they meet different people, they accept different ideas and points of views, they can easily grow apart... Thus communication is essential for good relationships. You want to know what is she thinking and feeling, you want to know about people she meets, you want to know about her friends, especialy those who have dicks...
* Future. Ok, you decided to be a provider. So shut up about it and provide. Bring income, feed hungry beaks, get a second job if you have to, listen patiently to complaining and bitching while holding her hand. Spend less time with your friends and more time with your family. That is your job, you volunteered for it, you fought for it so hard and now you can finally have it. Enjoy then, be a good daddy. You want to show your other half that you care. You want to plan things - next year vacations, next weekend movies, today's dinners,... you want to save money for your family future. You want to save money for your kid's college... Happy providing.
* Dominance. Of course that you want to remain in charge, dominant. The thing is, that you don't have to be dominant 24/7. You just show dominance here and there. You decide about big things - who cares what is today for dinner? But, you decide where to go for vacation in 6 months. You decide because you are paying.
* No. No. Fuck no if you have to say it. You tell her that once in a while. You piss her off once in a while. You show her who is the man once in a while. No is No - and there is no negotiation about it no matter how sweet she is. Watch her get pissed, and watch her get horny. You - of course - don't have to be an idiot about it either, nobody says that you can't bring her flowers the next day, take her for a good dinner or comedy show over the weekend, or make her feel great any other way... As long as she hears NO from you once in a while you should be ok.
* Her family. Get them out of your life. Move AWAY from them, especially away from mother in law. You don't want her mom to be part of your family, no matter how sweet she appears. Don't let her family tell you how you should live your life with YOUR family. Listen, smile, nod, show up in their church, keep great relationships with them - and then do what the fuck you were going to do anyway.
* Equality. You don't want to be equal. You want to be a man and you want her to be a woman. You want to be masculine and dominant, a guy who makes majority of important decisions. You you want her to be feminine and submissive, woman who is free to contribute to most decisions but doesn't really have the last word. No need to go overboard, as long as you keep some power in your benefits... say you keep 60 and you give her 40 - that is more than good enough...
* Is she a Giver or Taker? You want to find Giver, and you want to dump Taker. Giver will be doing things for you, bringing you things, cooking for you, she will be taking a great care of you - and you shall reward her for her good deeds. She is a great woman, she has a true heart, she is a woman to keep even if she is not as hot as Taker. Taker will be taking from you, you will be doing things for her and unfortunately (most men) will be rewarding her for bad deeds anyway... For what, for pretty face and nice legs? For her entitlement, only because she is hot? There are many great girls out there who don't have the looks of Takers but are really great Givers. You want girl like that. As far as long term relationship is concern, all Taker deserves is your boot, no matter how hot she is...