We want to somehow diversify our sex life with a girl. We tried light bdsm, but nothing hard. We're not really perverts after all. For example, no desire to try golden shower! Can you suggest something? 

Edging!  A slow teasing buildup is going to result in a bigger orgasm

Communication is key in any relationship, and it's no different in the bedroom. Talk to your partner about your desires, fantasies, and boundaries. Don't be afraid to express yourself and ask for what you want. Remember, consent is sexy!

My wife and I once tried an older hentai together. And in the process of watching them, we started flirting with each other. And during sex leave the hentai for the background. It helped us diversify our sex life a little bit. Try. I don't know what kind of plan would work for you, I like tamil sex videos. But you might want something newer