When I am working in a project knee-deep, I like to keep it on my front burner at all times, so I don't lose the flow. The way I do this is to tie all of my leisure activities together with a muse, who serves as a model for my current work.
Usually, this is an actor who reminds me of the looks and essential character of my male lead (the male character muse is because, most of the time, I am my own muse for the female character to some extent). Sometimes it takes more than one muse to get the complete picture, but usually it's one at a time, who, combined with my own memory and imagination, facilitates me building a fully fleshed (ahem) romantic hero.
Thus, when I am writing, all time spent not writing is spent communing with this muse. I read only books that have similar characters (though I don't read a lot when in the middle of a writing crunch), and I try to get my hands on the chosen actors' works, and watch them when I am taking breaks. The end result is that my imagination is constantly firing with ways to describe certain things, even in my down time.
This is one way I manage to produce as quickly as I do - it's not that I copy anything, just that I use various entertainments to give myself "working breaks" that make my writing time more productive. It also keeps me from getting distracted by other characters who might be bumping around in my head at the time, and helps me clear out the last muse to make room for the next.
I am not sure if anyone can recognize my muses in my works - I would be interested to hear any guesses, though. Surely, by the time they hit my pages, they are mere shadows of my impressions of fake screen personae, so they are well and truly removed from anything resembling reality by the time you read them.
But there's a little tip from me to you on how to create a world in your head and keep it bubbling between writing sessions. Let me know if it works for you, or if you have any tips to share... Or if you care to guess on any of my published muses. ;)