My comment was auto deleted for having YouTube links so I'll pm you those and post the rest of my advice:
Please please please get some prestretched hair. I wasted sooooo much hair the first 2 times. I've done my hair 3 times and I still can't taper the ends of the braiding hair without wasting hair/having uneven pieces. And buy a lot of hair. It's okay if you end up with too much but sucks if you don't have enough.
If you can, give yourself 2 full days to complete and be generous with the size. Your arms will burn and there may be times you need to undo and rebraid some braids because you couldn't grip tight enough or you used too much/too little hair. If you can get one of those thread racks, do it. You can portion out the hair beforehand and won't have to worry about braids being too big/small.
Make sure to moisturize the hell out of your hair and use some conditioning jam on your ends so they don't poke out of the braids. I didn't blow-dry my hair the last time I braided but I have pretty fine hair. I deep conditioned and moisturized the day before and put my hair in medium plaits. That made it straight enough for me.
Wow, I did not mean to write all of this lol. But I was really proud of myself for learning how to do my own hair. It'll be a long and frustrating process but after you dip the hair in some water and look at what you did, you'll feel so accomplished. Happy learning!