Well, start with the usual advice: Be near the edge of the floor, and visible to leads looking for dances. Wear clothes that are attractive but not blatantly exposing. Have good hygiene. Keep a smile on your face. Don't back-lead (well, maybe a little if you have a really green partner), don't criticize your partners, and don't be an on-the-floor teacher.
Now, let's talk honestly for a bit. At the studio that I dance at most often, I'm one of the more advanced dancers, and I know all of the regulars. I will usually notice when there is a new follower, and if she seems like she wants to dance, I will make it a point at some time in the first hour to go ask her. But if she's been sitting in the back all evening, and I haven't seen her dance at all... well, it's not like I'm intentionally ignoring her. I do try to dance with every woman in the house at least once. But, speaking frankly: When I return to the edge of the floor after a dance, there will often be at least one, and sometimes more than one, of the regular follows trying to get my attention for a dance. And, well, it's just easier: do I go seek out that unfamiliar follow who hasn't accepted a dance that I've seen, and doesn't appear to enjoy being there? Or do I dance with a familiar partner who is eager to dance with me? Yes, I will keep an eye on that woman in the back. But if I observe that she's turning other partners down, and just doesn't look like she really wants to be there, I may not bother.
And note that I will never not ask a woman, or turn down a woman who asks me, just because she's a beginner. There's quite a lot to be learned from dancing with beginners. And dancing needs ambassadors. If not me, who?
Is your instructor there? If so, can you get him to dance with you a few times? Instructors can be quite helpful in introducing you to other leads and breaking the ice. If an instructor asks me to dance with one of his students, I'll do it as soon as a dance comes around that is suitable for beginners. Similarly, if you introduce yourself to me, I will ask you. Maybe not right then, but I'll get to you. I will never turn down a lady who asks me, unless there's a damn good reason. ("Good reason" would be something like: stone drunk, very rude, or smells bad.)
So my advice is: you've got to seem like you want to be there. That means you may have to accept dances with at least some of those beginners, so you can be seen on the floor and those advanced dancers will know that you are there to dance. Make it clear that you want to dance, and you aren't just there to hang out. Talk to people. Tell them about what you're doing, what dances you like, and what type of dancing you're interested in, and so forth. Put yourself out there a bit. Then see what happens. It may be a process that takes a while, so be patient. But if you find you still just aren't having any success, maybe you need to look for another venue. Some places just have a weird vibe and there's nothing you can do about it.
If there was something specific I was having trouble following, we would work on it more so that I could either follow better or "fill in" when necessary. He paid enough attention during parties to help with things he saw go less than stellar, and he offered advise about how to deal with, oh, a leader who did things like go against the LOD. A lot of this is not obvious to a newish follow and not all students would want to spend lesson time on. I did and I let my teacher know that. Note that the student said she felt uncomfortable dancing with the beginner leads, not that she was too good/snobbish/etc. to dance with them. IME, it is worthwhile to learn how to do so.