At dance parties, don't be afraid to ask people to dance, especially ladies asking men. You'll find that if your honest about your abilities, more advanced dancers will dance with you and offer you advice or teach you new patterns. I've never turned down anyone, who's come up to me and said "I'm a beginner, would you mind dancing this one with me?." Or "Could you show me the basic?." To ask in the first place takes guts, and comes easier with practice. There will always be a few people who say "no," that is to be expected. You'll learn quickly who are obliging and who aren't.
The same goes for being asked to dance, tell your partner what to expect and give them a chance to step out and find someone else if they want. Most won't, but some will, especially on the more advanced dances like V. Waltz, and W.C. Swing.
Lastly, it's okay to refuse to dance with someone. Especially, if they make you uncomfortable. Just if you use the excuse of wanting to "sit this one out," you really shouldn't go to the dance floor with another partner. That's rude