Communication: Don't Send Out Mixed Signals
A lot of us send mixed signals sometimes when we're interested or not interested in someone, and that can be confusing. In addition, we often want what we don't have or can't get.
Without more information about your specific situation, I can only advise you to try and avoid these
conditions in your interactions with women.
As you say, initial contact is no problem; good.
Be Tactful but Clear With the One's You Don't Want
After that, if you're not interested, make that clear in a tactful, friendly way, say by clearly stating (if this is the case) that you'd like to remain friends only (some people can be good friends but not good romantic partners). If that would be difficult for you or for her, then, again as tastefully and maturely as possible, say that you just don't believe it'll work out, it's not a good match, whatever, and cut off contact. Even if she calls, if you believe it's not going to happen, don't call her back.
One clear, succinct cut-off is better than a string of time- and emotional energy-consuming back-and-forth "discussions" about the merits of a possible relationship. With all the other elements of your life going for you (job, looks, etc.), you should be able to make these decisions comfortably, securely, and adamantly.
Don't Get Anxious or Overbaring
On the other hand, if you like the woman,
try not to be overbearing. Don't seem anxious to get into a serious relationship, but try to show your feelings in the context of your normal interactions. Talk to her, but even more important, LISTEN to her.
Do things that you both like to do, ask her about her interests, and show interest in her answers (if she's a boring person, then I assume you don't want to continue). I'm making an assumption here, but I would guess that you're not necessarily looking for quick flings, but for a stable relationship, perhaps one that will lead to a family.
Don't Think About the Future too Soon
Even if you don't come out and say that, if you like a woman you may give off cues (or warning signs, as the case may be) to that effect, and that might scare her. Even if she'd like to head in that direction too, she may want to be reasonable and spend some time getting to know you first.
We can get very carried away when we like someone (believe me, I know), but it's important to take the other person's perspective into consideration and try not to put too much pressure on her. This is a good exercise for us as well, since it forces a little rationale into an emotional setting. It's always a good idea to try and keep at least one foot firmly on the ground while we float away on the clouds of an exciting new relationship.
I believe everything happens for a reason, and I trust you'll find what and whom you're looking for in good time.