When asked "What are you doing?" never reply with "Nothing", always appear to be busy even if you are not. This will make you seem to be much more interesting.
Never stay on the phone for a long period of time (unless a serious relationship has already been established) or you will appear to be a boring person because you have nothing better to do.
Never act submissive because you want to be the "Nice Guy". In the real world (outside of Hollywood) nice guys don't get the girls, so stand up for yourself and don't get used. However, don't become the "Jerk" either, the goal is to be likable while also showing strength by always expressing yourself and your opinions.
Never, and I mean never, say "I love you" first. If you say these 3 words too early you can easily change a great relationship into an uncomfortable one (for the both of you), and possibly destroy it.
Always keep things happening in your existing relationship. Try new things (not only sexually) and never become lazy by just sitting around watching TV every night. If your girl becomes bored with the relationship she will leave or cheat on you. Remember "It's easier to steal someone else's girl than it is to keep your own!"
Never act serious at the beggining of a new relationship. You may begin to develop strong feelings early on, but you don't want to scare your dream girl away by coming on too strong. Just try to relax and have fun while allowing your relationship to blossom at a steady (but slow) pace.
When going on a first date, never go to a club or movie because you want to spend this time talking to her and using the player skills you've learned, which can be limited once you go to these places. Take her somewhere fun (during the daytime, such as miniture golf, the beach, etc.). This will lighten the tention and make both of you more comfortable.
Never attempt to have sex with her unless you know (for sure) that it's yours for the taking. If you try and fail, chances are she will be extremely uncomfortable around you the next time you get together, and probably never return your calls or avoid you completely.
Always change the amounts of attention you give her. For instance: Give her your undivided attention for an extended period of time one day, and appear to be too busy to even talk to her the next. This will drive her crazy, and you will be on her mind the entire day. She will be wondering if she said or did something wrong, and she will become much more interested in you because she won't be able to think about anything else.
Once you are in an established relationship for a relatively long period of time say this to your girl: "You know, your probably my best friend". She will most likely burst into tears and will love you twice as much for saying it. *note* Make sure you say this at the right time. For example, saying this while shopping at the mall would be a bad idea, but saying it late at night while your laying in bed would be on point like a fax machine.
Never bring a woman to a really expensive restaurant for any of the first few dates. You may think that you are impressing her, but all you are really doing is adding to the tension.
Never... ever... borrow money from a woman. Even if she is a long term girlfriend and you need it badly. Women want a man that can support them in any situation. In a woman's mind "For rich or for poor" actually means "You better get rich, and if your poor I'm gone". If you borrow money she will be thinking "Hows he going to support me when he can't even take care of himself". Never let her know if your in financial trouble.
Never become obsessed with a particular woman you've just met, no matter how hot she is or how much she seems to like you. If you think about her too much, you will begin building up tention in your mind which can effect how you act the next time you see her, and that is when you want to be on top of your game, not looking like an idiot with nothing to say.