In my experience 'maybe' means no. If you get a maybe from a chick just tell her to let you know when sh!t isn't up in the air, then the ball is back in her court.
When I date, I plan what I want to do and were I want to go, because it's my money and I'm spending it, and time, on things I am interested in. THEN I think about what chick might be fun doing what I have already planned... then I ask them. So when I'm asking out someone, I have a specific thing and time I want to do. If she can't make definitive plans, then just tell her 'maybe' another time. You don't have to be an @ss about it.
It's possible she really does have a bunch of balls in the air already and doesn't know. If she likes you and is interested, she will tell you specifically what she has to clear up and move things around to make it happen, and will say she'll get back with you and give you a specific time when this is going to happen. In that case if a chick needs a day or two to figure sh!t out (like child care or to cancel something else she has planned) AND you can wait without causing problems then go ahead and give her that time... but it has to make sense. Tell her you need to know by a set time, and if she doesn't call you back before then... move on the plan B. If she comes back after you have already asked someone else, just tell you made other plans, but tell her next time something like this comes up, you'll ask her again.
You can't do this if your plan is "Hey let's meet up sometime." Have a specific thing and time you are inviting her to.
Example: I just got tickets to see Def Leppard in concert at the end of the Summer. I'm going, and someone is going with me. I know one chick that likes them... I will ask her first, not because I'm trying to get her, but because it's more fun spending time with someone that likes what you are doing. She's getting invited first because I think she would be the most fun. If she can't make it... no problem, I'll ask someone else that I think might be fun. If I run out of chicks that won't make definite plans then I'll take my cousin... or one of my daughters... it's not a big deal. But I didn't get these tickets to impress someone, I got them because this is something I want to do.... that's the difference.
You should never find yourself in a place where you are waiting on a chick to work though her emotional BS to make a fvcking decision. You are on the fun train... and the fun train has to leave the station. Get aboard or get left behind.... and maybe when the train pulls in again she won't do this to you again. You have to remember, most dudes she is dating will wait around, she's used to guys acting like this, she doesn't think there is anything wrong with keeping you waiting because she gets away with this with other guys. It's really not her fault, other men have trained her to act like this. If she runs across a guy that justifiably gets butt hurt about having to wait for a decision, then she justifies her actions by saying the dude was an @ss anyway.