Women are definitely a species on their own. They're hard to read and understand, but like most things in life, you can't live with them and you definitely can't live without them. These are phrases to use on a woman that's already in your life to redeem yourself from a fight, or just to make her happy and hopefully make you lucky.
Compliments are always a safe route to go down with any woman. Females naturally have the need to hear words confirming your feelings for her, relationship with her and how she looks. Women love to be complimented on everything and anything, and giving her compliments will help you in the long run. Not only will it make your girl happier, but she will feel less needy and insecure as she feels confident in herself and your relationship. Why? Because you are telling her.
You also want to show your commitment to her, no matter what stage in the relationship that you are at. Women have that natural insecurity, or what some may call "Daddy Issues" and often fear that their men will betray them, leave them or cheat on them. Show her that you are committed to your relationship and your feelings and this will again, only benefit you in the end.
Speaking of jealous, women love a man that has a little jealous streak in them. You definitely don't want to act suspicious or even worse, obsessed, but having a little bit of jealousy shows your woman that you care about what you have, appreciate it and know how good it is. You may not be worried about losing her and have all the confidence in the world about your relationship, but showing her that you don't want to lose her to anyone, will make her feel more loved and secure in your relationship.
Lastly, it is extremely important for you to show interest in your woman's life and the easiest way to do so is by asking questions. It can be as simple as asking her how her day went, or remembering something that she had mentioned previously, and asking her about it. She will be impressed with your listening skills and be grateful that you are there and take an interest in her wellbeing and life.
These are all such simple things that will ultimately make you a happier man. As men often say, "A happy wife is a happy life!" Joke or not, it is very true!