^ As of now, I don't know how to answer this question. I'm not saying this to boast myself. But I think no matter how good you are to your boyfriend, if he choose to do some shitty stuff, then it would be useless.
But this is what I do with my previous relationship.
1. Be understanding
. I know this what should apply to women in the first place but even guys didn't understand about themselves. Understand your guy why he is late for the date; why he do such silly things. I know it's hard but it's worth it to avoid conflicts. Also, if your guy is in deep problems and he needs to be alone, don't panic! Let yourself busy. Sometimes a man wants to be alone when he is problematic. And they don't want you to intrude. Let him come to you.
2. Be Appreciative.
Small or simple things, if you appreciate what your guy did to you, it will boost his ego. He loves his gf more because he thinks he has given importance by appreciation. Say to your guy, "Salamat sa time ha kahit di tayo matagal nagsama ngayon. Naappreciate ko yung ginawa mo."
3. Give freedom but set limits.
A man doesn't like a woman who acts like a spy or a tail asking about his whereabouts. If his GF is like that, the guy thinks she is acting clingy and that keeps him away. Set limits. Of course guys also loves women who SLIGHTLY control them. He thinks his GF really loves him because she is concern with him. If you're not a jealous person, try to act one, even in RARE cases. He loves to know that you are jealous with other woman. But be careful, just slightly.
4. Be a wife.
It doesn't mean the literal "wife". Just treat him like you are a wife to him. Cook his fave food. Prepare the table for him. Press his clothes, if he happens to stay in your house and he needs to change one. When he is soaking wet with sweat? Pat him dry. (Grrrr...nakakamiss ito)
5. Say "I love you" regularly
. For at least 3 times a day, you have to tell him that you love him NOT that you adore him.
6. Don't give in (easily)
. This is my mistake. Act like you're irresistible
. Even if you're already his GF it doesn't mean you will go with the flow and gives what he needs. If you don't like what he requests on you, refuse him. Guys love challenges and they want to pursue more on you if you are playing hard-to-get sometimes. Also, be a mysterious GF. Let him discover more about you.
7. Be honest.
I know most guys are good liars. But as much as possible, be honest with him. If you don't like certain things, say it. Be true to yourself. Men don't like women who are faking.
8. Be his buddy.
Yeah, I know, men don't like shoppings, cosmetics and other feminine activities. But they want you to join them in their activities too like playing computer games, basketball or just chitchatting about cars, sports and so forth. Hang out with him if he would like to watch basketball games or just do some men activities.
9. Be a mother.
Men are more closer to their mother. That's why they like women who are acting like a mother BUT not too strict. Just let them know that you care for them. If they do silly things often, you have the right to scold them. Say, "Huwag mong masamain kung magagalit ako sa'yo dahil ginagawa ko lang ang dapat dahil mahal kita." Guys love that line.
10. Open suggestions
. If the two of you have misunderstandings and quarrels offer suggestions and ways to solve your problem. Say "Okay, para magkaintindihan tayo dahil ayoko ng away at walang gusto sa ATING dalawa na mag-away tayo, ganito nalang kaya ang gawin natin kung ok sa'yo."
11. Be humble.
Okay, here you are, fighting with each other. If your guy happens to shout at you DON'T shout back. I know girls last words means end of the fight. Instead of talking back, tell him "Di ko gusto ang ginawa mo sakin. Ayokong patulan ka kasi alam kong mainit ang ulo mo at ayaw kitang kausapin unless di ka na galit." Also, when he is upset with other reason or person, try to remain calm. I know you are worried also. If he said something bad about his boss, zip your mouth. Just listen to him. He will just notice it that you are not responding him. Your presence is just enough for him. If he wanted you to speak also, then that's the time to share your thoughts.
12. TRUST HIM.
I intend to make this the last thing because this is the most important part in the relationship. You MUST trust your guy no matter what. If you don't want to give him your full trust, at least act like you're really trust on him. You have to. Even if it's hard for you. Because a guy normally have high confidence in himself. Whatever he wants to do, he knows he can do it. Let him to prove himself that he can overcome whatever he wanted to try or do. Trust him that he loves you. I know a woman, often thinks like a paranoid because she is thinking that her man might seeing another woman. It's not a healthy attitude.
There are lots of ways to become a good GF. What I give are the most important qualities a woman should have. I didn't mentioned about the physical attributes because it's just a temporary. What is more important is the attitude of a woman. Even if a guy gets easily attracted on beautiful and sexy woman, still he will find the attitude.
I hope this will help you sis. I've done this to my previous BF (latest). So far no major quarrels and the relationship is very smooth sailing. It's just it didn't worked because he has personal struggles and of course, he's a piece of s***t and i***t. It's not my fault anymore. At least I do good to him.