Big Slouchy Hat

(Warning: Amateurish photography)
I found an adorable slouchy hat on Pinterest and thought I'd give it a go.  In my opinion, the photo of the purple hat, and the directions given, bear not the slightest resemblance to each other. It's a good thing I'm rather innovative when I crochet, or this would have been a disaster. (In other words, the blogger's directions are useless, especially at the hat band.)
Use a J hook and worsted weight yarn. Begin with a magic circle. Here's a youtube tutorial for that, if you need it. I think a magic circle is the best method to begin a round crochet project like this. Put 6 single crochets on your circle. Add 5 more rows of single crochet, putting two dc's in each stitch from the previous row when possible, without buckling your work. It should be tight, but stay flat with some pressing. I made mine too tight.

(Sorry about the color shift in the photos.) Now I switched to a larger hook, an N. It's probably best not to switch hooks quite yet. At this point, begin using triple crochets, alternating one, and then two, tc's in each stitch from the previous row. Do two rows like this, until the crown of your hat is about 6" across. It will have begun to ruffle quite a bit; that's fine -- this is the extra volume of the "slouch" in the hat.

Keep going with your triple crochets, and at this point (row 8, counting your magic circle as row 1), definitely switch to the larger hook. Only put one tc in each stitch from the previous row. I did 5 rows of this. The hat's edge will begin to tuck under nicely, and it will look really large.

The underside:

Keep placing it on your head until you feel it is the right size for you -- that the addition of a band will place the hat correctly on your forehead.
The band: I switched back to my J hook. I started by working a dc in each stitch from the previous row, pulling the tension on my yarn a little with each stitch to help "tighten up" the hat a bit and rein in those floppy tc's -- I did that for one row. On the next row, I did single crochets, working only every other stitch; this was the row when I was trying to reduce the hat's brim to the right size for my head. Try it on several times so you don't reduce too much.
Once you get the edge the right size, you can add a nice band. I decided to do 2 rows of alternating front- and back-post double crochets, to give it a ribbed effect.

I added a fun, large button for decoration.

The band is stretchy and fits perfect on my head -- but I'll be selling this at the market.

Not a very attractive photo, but you get the idea. Hats are really not my thing.

And from the back. I'm cranking my arm around behind me to get this shot :)

See how the hat pulls from the middle, and has so much volume in the bottom? That may be from the way I have it sitting on my head, but it may also be from switching to the N hook too soon after that tight first disc. If I make another one, I'll try to tweak the pattern a little, and see what happens.

This is the same Simply Soft red yarn I used for the bobble stitch ear warmers, and the drapey shawl.