Personally, I think it's more romantic not to ask, girls tend to agree. So Stormy, how do i confirm she likes me before I kiss. Well pardna, it's easy.
1) slowly approach her
2) Hold her chin and gently tilt her head up to face you
3) Slowly move your face down your lips closer to her.
At this point if she closes her eyes, or is silent, or is looking at you, that means it's time for the kiss.
4) With your lips pressed together kiss her
from here on she will either put her arms around you, be shocked, blush, or be confused.
If she puts her arms around you, reciprocate
If she is shocked, take a step back and look at her, wait for her to smile or see her reaction
Now, if after step three she is hostile, no kiss.
If she is saying something along the lines of "What are you doing?" kiss her while she is in the middle of saying it.
I would say this one is worth the possibility of a slap, although you can only do it during REALLY romantic or quiet moments.
Now, otherwards, if you can't do the epic chin grab, look at her smiling, a sexy smile if you can manage. When she asks what lean closer and ask if you can kiss her. If she says yes, then keep playing basketball... er wait KISS HER YOU DORK!
If she says no then there will be a lovely moment of silence and then you'll react as normal. If she says an inbetween comment than just say, "oh" and keep on going.