Be yourself. I was single in my mid 30s about the time that the 'cougar' trend started, and it was just annoying to have younger people hitting on me because it was suddenly cool. Have interests of your own, goals, and things to talk about other than 'wow, you're so awesome because you're older'. Have interests of your own that match up with the person that you're with. In every relationship there's always going to be some give and take and non-overlapping of interests, but it can get wearing if your partner doesn't share the same references that you do- music, books, interests, life stages etc. She may be focused on her career or kids or personal interests when you're studying for an exam or worrying about paying off student loans etc.

And be sensitive to your prospective partner's life. Maybe in some circles having a boy toy is a plus, but from what I've seen, introducing him to your kids/family/colleagues can be embarrassing. If you've got an age related fetish or some reason why you aren't interested in women your own age, make sure that you make it known very early on. There's not much that's less sexy than an inadvertent 'mommy' or "Mrs. Robinson" at the wrong time. Older women don't hold some magical key to your sexual awakening or fulfillment or whatever you're after...I'd concentrate on the individual, rather than their age. Everyone has their kinks and sexual preferences, but "40+ women" is so broad a category to be meaningless. I'm 50 and I have 40 year old friends who have children who are already out of the house, or who have never had a partner, or who are new parents or making major changes in their lives. 40+ women don't always have much in common, so I'd concentrate more on actual people than looking in a specific age range.