If he's your best friend then tell him when it's just you and him together just hangin out, but don't be obsessive because that might creep him out and possibly ruin your friendship. Just play it cool(: and if he likes you back maybe you could give dating a shot(: but if he doesn't feel that way then tell him that you care about him alot as friend. He should understand where you are coming from and you 2 can remain bffs(: Good luck!