Don't focus on actions so much. There is a reason a lot of buildup is killed by smut authors, especially in a romantic setting. They end up focusing on the actions of the characters in the scene and over indexing into it. People love cute romance, so there is no reason to not do the same thing in a smut scene.
It's possible to do an entire scene without even mentioning a genitalia or body parts, depending on composition. I once did a sex scene as a musical score. Every touch was the plucking of an instrument, and the song's buildup was leading towards a climax. Their emotions were incorporated into the music.
I am not saying to never use action, but just remember why people read cute romance and apply it to smut. They want to see how characters react to being touched. Think about that first kiss in a story you read and the lead up to it. Now if you are writing fetish content, it might be completely different.
Another tip is to read sex scenes that people think are great for the genre you are writing. Even if you never experienced something, you can write about it by reading other people's take on it.
