"First, we've got to create the mood." Sebastian to Ariel in the Little Mermaid.
Dim lights. Candle flickering. Soft music. Chocolate.
Creating the mood, for me, starts with...words. I'm talking about writing guys, with the lights on.
Before I sit to write a scene, I take out my cheat sheet. If you don't have a word cheat sheet I would highly recommend creating one. Angela Ackerman over at the bookshelf muse has an awesome list of words to get you started. I got mine from her thesaurus list as well as in books. All kinds of books. Yes, I'm a nerd and read with paper and pen to jot down those wonderful words that inspire me.
crouched, settled, stillness, pain, balance, skittering, movement, slammed, slapped, pitched, howled, coiled, slashed, drifted, seared, kick, smacked, thudded, clenched, swayed, stalked, reeked, clang, battered, sensed, ignited, crushed, crawled, exploded, side stepped, snuffed, burst...and on and on.
What mood have I created? Don't think you want to blow out the lights just yet. LOL.
When I feel stumped, I take out my list of words categorized by purpose of scene and read through them and let my mind paint the rest, and then I write.