Well, the first thing to know is that you want to be sanitary. So, you'll be sanitizing your equipment. Not sterilizing. Sterilizing is for killing way more microbes (like for surgical equipment via an autoclave) than we have to worry about. Star-san is a great sanitizer.
We have to sanitize anything that touches our wort post-boil. So, NOT your brew kettle, spoon (until after the boil, if you're using it), grain bag, etc.
What I do is use the convenient measurements on the star-san bottle, and mix up about 2.5 gallons of sanitizer right in the primary. Anything you're using after the boil (hydrometer, strainer, spoon, wine theif, airlock, etc) can go in there. Before I put the equipment in, I put the lid on the fermenter and shake it up well, and the foam covers all the surfaces pretty well, so you can see it. Then, put my stuff in the sanitizer. If I'm using a siphon, I pump sanitizer through it and coat the outside of it well also. After everything is sanitized (I leave it sit from a minute to the entire time, depending on what I need, like maybe the thermometer to check the wort temperature), I pour some of that sanitizer into a spray bottle and spray my clean kitchen counter. I put a clean paper towel down, and stick most of my stuff on there, ready to use. The rest of the sanitizer goes into a one gallon milk jug for next time. Be careful with your hydrometer- it's slippery and round, and easily will fall right off the counter. I sanitize the hydrometer jar, and put the hydrometer into it while waiting for my wort to cool.
I'm sure there are some things I'm forgetting, but that's pretty much what I do during brew day.
