I saw patterns for similar scarves on Pinterest, and I customized it some to suit my taste.
I used a chunky yarn (some kind of Wool-Ease yarn from JoAnn Fabrics).
You will start with a chainless foundation - actually, just make one row for each of the 8 strands (I suppose you could make the rows wider if you wanted to make a wider scarf, but I haven't tried it.) Read about how to make a chainless foundation here. You will want to do the chainless DC stitch for approximately 150 stitches (longer or shorter to suit your tastes for an infinity scarf. It will end up longer than you think!) If you want a normal scarf, you will probably want to make it longer.
I did careful step by step photos, but unfortunately, only for the first time I braided it - which didn't end up lying flat enough, so I redid it.
After you make 6 strands, single crochet across the ends to attach them - so it looks like this:
Make sure you crochet the BEGINNING ends together, or they will be a pain to unravel later when you need to match the ends up! Don't ask me how I know - haha!
You can then start braiding the scarf - don't pull too tight, or the braid will bunch up instead of lying flat. I have two diagrams: one for a six strand braid and one I accidentally drew first, for an eight strand braid.
Basically, work from the left: under, over, under - then from the right: over, under, like you are weaving.
The eight strand braid is similar. Work under, over, under, over, from the left, then over, under, over, from the right, in the same cross-weaving pattern.
When you get to the end, all of the ends will not be the same length. You can unravel them until they are even. This is why you wanted to start braiding at the beginning of the strips instead of the end!
When you are finished matching them up, they should look like this. Single crochet across the ends like you did at the beginning of the scarf (you just might want to pin them so they don't unravel while you are attaching them).
After this, you hold both ends of the scarf together - make sure it isn't twisted - and single crochet or slip stitch the ends together to make the scarf an infinity scarf, or leave it as is if you just want a normal scarf.
Good luck! If you are confused, I'm happy to help.
For the hat tutorial, click here.