That’s your choice! Think about what you’d be comfortable with. A lot of guys prefer it when you swallow because they like being in your mouth until the very end and it’s also really hot for them to watch you.
You can swallow, you can take it and then spit (some of it does accidentally go down your throat though and you actually taste more of it because, with spitting, it swirls around in your mouth for a longer period of time), or you don’t have to take any of his cum at all!
If you’re not comfortable with it then DO NOT SWALLOW. You don’t have to, it’s not a requirement, and your guy will be perfectly fine with it.
Just discuss it with him before you start and make sure that he knows to pull away and finish himself off (or you can do it with your hand) into a tissue or somewhere on your body, whatever you want.
Test the waters. Try actually getting the point of climax with him (no swallowing, he jerks off onto something else) and after you’ve seen it the first time, decide whether or not you would mind having him cum in your mouth the next time. If you don’t want to do it, don’t do it. It’s that simple. Just communicate that with your partner and make sure he’s on the same page so there are no “surprises”…