This is ridiculously vague, because that's just the way I do things, and I'm not good at crochet terms because this is my first in ages, but I will try because I'm so flattered that you asked!
1) make a loop of about 6 chain stitches
2) single crochet in each
3) increase every stitch for about one round, then every other stitch for a while, then every third or fourth, until you have something bowl-shaped. I didn't mark the start of the round and did it all by feel (I know, I'm bad), but my snowmen still turned out pretty symmetrical. If you want to be more exact, there are tons of patterns for crochet balls to be found. Practically every cute animal includes one.
4) Do a few rounds of just plain sc until it looks like it's time to start decreasing (when you have half a ball, or rather a little more than half a ball)
5) decrease in the same pattern as you increased - maybe every fourth stitch at first and then closer together until you decrease in every stitch and have a small opening about the size of a snowman neck
for me that was about 10 stitches
6) stuff snowman body with whatever you have handy, I used little bits of an old t-shirt. But not too full, you have to be able to keep crocheting
7) one round of plain sc, then start increasing again for the head. Repeat the procedure for the body, but stop increasing a little sooner so the head is smaller
When you have a small opening left, stuff your snowman some more. The crochet hook is good for this. Massage into a good shape, you can undo some misshapenness with the stuffing.
9) Crochet the opening closed
10) Embroider eyes and nose (basically three dots, one orange and two black. I tried to improvise a 3D carrot shape for the nose, it worked pretty well once and less well the second time)
A naked snowman! Make a loop for hanging with the end of the yarn, unless you want a hat.
Cast on 4 stitches, knit garter stitch until scarf fits snowman, tie.
Scarf 2 (keyhole scarf - I like the look of this better)
Make two crochet chains of snowman scarf length. Sew together through the loops on the back, leaving an opening near one end. Pull other end through this opening to keep the scarf around snowman neck.
Knit a triangle that looks about big enough to fit around you snowman's head. It doesn't have to be exact, you can sew his hat on
sew down one side, attach to snowman, make loop on top.