Ugh god i know that feel. My hair is almost to my booty and I always wanna do fun stuff like braid it-- the problem is my hair is really fine and likes slipping out, getting flyaways and CREASES UP THE WAZZOO.
Things I've done are 1.) take a shower 2.) blow dry it to mostly dry 3.) brush the shit outta it 4.) put some anti-frizz mousse in it 5.) brush again 6.) separate the sections using clear hair bands at first 7.) braid it and tie it off 8.) cut off the plastic bands 9.) spray lightly with hairspray and BOOM ROCKIN IT
I have the same problem! I hope other people have answers lol.
Most people start off with big chunks, start it with smaller chunks, almost like a corn row. Then just braid like a normal braid, picking up more hair as you go along, it'll make it thicker as you pick up more. Just pick up the new bits of hair in the direction you want the braid to go on.
Bigger ones look easy, but a lot of people find smaller ones or corn rows easier, so try practicing with smaller sections first if that helps.