Boosting relationships is easy, just chat about the things they like and that provides a significant boost, or with the family you can just give them money. If it says "Drained" or "Your Relations are too depraved", then you have exhausted that action and there is no (mechanical) benefit to doing it any more. If you are losing relationship points but increasing sexual tension you are on the right path, if you are just losing relationship then (generally) you are not. Without knowing specifically how far you have gotten, I can't really offer any advice, and to be fair I'm not sure I will remember specifically what I did to trigger a certain scene, because for some of the initial characters, the events happened a long time ago, but feel free to ask anyway, if I can't answer, there is a decent chance that the answer is either buried in the thread somewhere or someone will know.
