Catch her doing good things. That sounds silly but simply showing a positive reaction to everyday things will help. Small, casual touches, not flirty, during conversations like when you emphasize points. It keeps touch and physical connection alive. Important, smile! I hate it when people tell me that but it goes a long way. Plus it puts you in a good mood if you make a habit out of it. Small compliments. Tell interesting stories about your day. Look her in the eyes. Use body language like mirroring. I suggest picking up a book on flirting. Not all flirting is sexual or even romantic. It shows connection and emotional intimacy. Be very aware of criticism and bad habits--like rolling your eyes (one of mine!)--that you might not otherwise pay attention to.
This won't win anyone over all the way who would otherwise have their guard up. It's a start, though. Be careful and don't overdo it. Just be kind and interested but not too interested.
Hope that helps.
~Mark
Me: 38 W: 34 Together: 9yrs 1st M: may '03 1st D: april '08 1st bomb: june '08 remarried: oct '08 2nd bomb: aug '09 --(W asked for D one week into 3 mo. trial separation which was meant to save our M)