Foreplay. I don’t mean with your characters (although that’s fun stuff to read) I mean your readers. Don’t just toss them into a sex scene. Seduce them first. Use your sensory writing to evoke a mood then mercilessly push buttons to get them hot and bothered. Tease them. Manipulate them. Make them feel the warmth of a lover’s breath just under their ear so they’ll shiver. Make them want a lingering touch next. Take your time. Do a thorough job of it. It will leave them with the impression of a great sex scene even if you never describe a sexual act.
Reflecting on your work will give you a lot to tackle in your second draft, and expanding on the ideas your subconscious seeded in the first draft will add depth to your story.
Deleting characters can cause huge plot problems. Let me restate that. Deleting characters should cause huge plot problems. Everyone on the page should be there for a specific purpose, like cogs in a machine. If you can remove one and nothing changes, they shouldn't have been there in the first palce. (I'm talking about main and secondary characters here, not the extras in the background) When I removed the two from mine, a key part of the plot suddenly didn't happen, so I had to transfer their actions to one of the remaining characters. Different characters have different motivations even if they do the same thing. (For example: I eat sashimi because I like it. R will only eat it when it’s served to him and it would be rude to refuse it.) That meant, yes, exploring the motivations of the character and making sure they made sense. That was a lot of work, and typically the kind of stuff you do as you're writing the first draft. Maybe instead of calling this one my second I should have called it First Draft version B.
Between changing the sequence of events and eliminating characters, the second draft left me with a lot of work to do. (Thus the five drafts.) I wouldn’t have made those changes if I hadn’t strongly felt they were necessary. Unfortunately, I can’t explain to you why I felt they had to be made or how you might sense that your story arc needs that kind of revision. (I hope for your sake that it never does. This is why I often say "This is what I do, but I don't recommend it to anyone.") Readers might feel that the way a story was told was the only way it could have unfolded, but writers know that there were many possibilities. More than one path can lead to the same destination. Part of choosing the path is talent, part of it is craftsmanship, all of it is the mysterious (wonderful) process of creativity.