First off all let me straighten something out. Hooking up means making out, it does not mean having sex, please stop making this mistake in the future. Moving on here is your playcard after making out with someone and your steps to following up.
Met at the bar and made out there
Don't count on much progressing from this if you actually dig the girl. This is something I have done in the past but don't plan on doing again. Everyone sees what your doing and it makes you look bad unless the girl is really hot. You can give people the wrong idea about what your all about. Anyways, if you get here number try to follow up but this is likely let it be and move on. No phone number exchange is required here.
Met at the bar made out at either or your places
Girls love to just make out but it can be boring if it doesn't progress after awhile. If nothing progresses its best to part ways on the night unless you are kinda stuck without a way home. Sometimes its okay to tread softly and build slowly. Personally I will always follow up in this case if I ask for the girls number. Phone number exchange probable.
Met at the bar, stayed the night
You seem more committed at this point. You hung out all night and woke up next to each other. It's kind of hard to not have any follow up her from either side. On paper this should lead to seeing each other again so long as you are not saying what did I do?
Your Friend of Friend and Will See Each Other Again
This is a tricky one and hopefully you thought this one out before you proceeded. If your not interested and got with them once communicate it to her and come clean. If its an ongoing thing that's casual make sure you two are on the same page. You should always be considering your surrounding friends in these cases. If you are really into the girl, then still tread carefully and slowly it will be more rewarding in the end.
Who asked for who's number? This is one of the few times I will defend the opposite sex. Generally speaking if a guy wants your number he will ask for it. If he knows he is going to see you again though it might be in his best interest to wait it out. When girls offer the number first it can shift the balance of power to the guy. I won't say it makes you look desperate because it doesn't. However, it tends to make you seem like the one more interested. But thanks for taking the pressure off. When I ask for the girls number, I call or text. If you stick it into my phone or force me to take your number and force me to say I will call, your asking to sign a contract under duress. If I want the number I will ask and if I voluntarily say I will call or text I mean it and most people probably do.