Talking about interest topic is the cheapest way to increase the relation of girls toward you (it can range from enemy to best friend).
Every girl has different interests, you should talk about them regularly to increase relation. It doesn't cost time or energy to you, but it DOES increase the stat. You chan check it from the phone or if you prefer you can hover on a girl when you see her in any location. It will show you a small window listing name, relation level and sexual attraction level. Try and you'll see it changes over time if you spend enough effort to talk with them.
Another way to increase relation is chat (some options, generally asking "How are you") or giving money as a gift (only with mom and sisters)
In this game options available change according with the relationship stats, so you should try to talk and interact with the same character at different times and different levels of relationship to see if it unlocks some new option/scene.
Sex attraction increases when you interact with the girls (you can often repeat the scene up to the point where it gives you no more bonus). Higher sexual attraction enables other scenes.
The color in the talk/chat/request menus has no meaning, only the text matters.
An other advice, use the phone under "my status" to check the conflict stat of you and your 3 family members. If conflict between any of you is too high, switch rooms or you risk game over. Double sized bed in you room gives you access to new scenes (you can ask for it from the motel manager) but increases conflict with your roommate faster. Btw, making gifts of money decreases conflict as well
If you have any other question, feel free to ask; just please try to chill out a bit, your last posts seemed a bit too angry.
