Here are the most basic ways to Invite someone on a date, or Accept/Refuse an offer in French:
Ça te dit quelqe chose de....? (What do you say to...?)
Ça t'intéresse de...? (Are you interested in...?)
Est-ce que tu es libre....? (Are you free...?)
Est-ce que tu peux/veux...? (Can/Would you want to...?)
Oui, je veux bien (Yes, I would like to)
Oui, je suis libre (Yes, I am free)
Oui, j'aimerais bien! (Yes, I would love to!)
Non, je ne peux pas, parce-que... (No, I can't, because...)
Non, je ne veux pas! (No, I don't want to!)
Je suis désolé. (I'm sorry)
Non, je suis occupé (No, I'm busy)
Now all you have to do is find a cute French guy (or girl, I suppose) to practice with. Good luck and enjoy.