The best solution with this is to act casual and not expect too much.
The truth is that if you sit back and hesitate, you'll miss a chance.
The only way to learn is to try and experiment.
The first time you ask a guy out, it is always a bit awkward.
The second time, you are more comfortable, and after that, you keep on perfecting your "asking out" skill.
It is a "move" you have to practice to get it right.
It is always 50/50.
There is no guarantee that he will say yes because he can have dozens of elements in his life which stop him from dating you right now.
There is only one way to find out: Take the step!
How do you do that?
If you know where he hangs out, go there and if you see him, walk straight to him with a big smile:
"Hi...! How are you? Good to see you!..."
Don't focus on the date thing.
Simply establish a connection first.
Chat for a few minutes and then say something like:
"Was fun seeing you again..."
Then write your number on a piece of paper, look at him straight in the eyes and say:
"Call me. I know you already tried once... But guaranteed. This time I'll say yes. You are a fun person and I would like to see you again. It will be nice"
It's casual, spontaneous and it does work wonders.
If for some reason he does not respond, stay cool and alert and keep your options open.
If you expect too much, you systematically get hurt.
So simply try it out as an experiment and if it does not go the way you expect, drop it and focus on someone else.
The art of dating has lot to do with going with the flow and responding to opportunities when you see them.
Sometimes, you can rationalize too much when in fact only action (even imperfect action) will give you the answer.
Go for it!