generally you shouldn’t really, let it dry in its curls and it’ll be less frizzy/hard to manage

I just use my fingers to detangle and prevent white guy dreads in the shower and then as ergot said, let it dry in its curls.

Look as someone who has in the past two years grown his hair out, let me tell you:

• Don’t comb that shit dry, ever - unless you really want volume (I mean - I have a habit of running my hands through my hair and as a result I will always fuck it up like 30 minutes after I finish styling it)
• For dreadlock prevention, try a satin pillowcase (my sister swears by this) or a nightcap. I personally don’t enjoy using either, so I bought this electric detangler and run it through my hair to detangle like once a week.
• for parts of your hair (the back of my head is where I fight this the most) that naturally just want to get tangled and form proto-dreadlocks as soon as it starts drying, like others have said - a nice leave-in conditioner and a comb is your best bet.