First read Soft velvet laptop sleeve?
Sometime the yarn is completely tangled in the middle of a project. It takes hours to untangle it. A great tip of my mom was : Just before you begin with your project, make a new ball of it.
First read how to crochet a circle?
Don’t start always with doubling the single crochets on the same place, this way you avoid to make an 8-hook instead of a perfect round circle! By example, start the 6th row with only 3 single crochets and then crochet 2 single crochets in the same stitch, from then start counting from 5.
Start making a magical loop with 8 single crochets as the first round. For the second round, start with two chains, counting as the first single crochet. Thereafter put two single crochets in each single crochet of the first row, thereafter crochet a single crochet in the single crochet of the previous row. Repeat from * to * until the end of the round. Close with a slipped crochet.
For the third row again start with two single crochets, crochet two single crochets in the next single crochets of the previous row. *Thereafter crochet two single crochets in the next same single crochet of the previous round. Crochet two single crochets in the next two single crochets of the previous round*. Repeat from * to * until the end of the round. Close with a slipped crochet. Do the same for the next 7 rows but increase by one stitch for the single crochets into the separated single crochets of the previous row.
Find a very good explanation here!