handjob/bj advice!? 😲

My boyfriend and I havent had sex yet, we want to wait a while, but we do other stuff (you know what i mean), it seems he always precums a little when i give him a blowjob but he never really finishes even if hes close. I dont stop or anything at least for another good 10-15 minutes

How can i make it better for him to make it feel more pleasurable?

Tip/advice please!! 😄