Great advice from everyone, so I'll keep this short:
I too got started brewing with William's Brewing kits. I made 5 kits before going all grain. My biggest complaint with those kits: while I learned about fermentation, sanitation, and some of the brewing process, the recipe is totally hidden from you. I didn't know what hops I was using, how much did the packet weigh?, how many IBUs would that contribute?, what type/quantity of grains were mashed to create the extract? The instructions kept so much a mystery... I wasn't cooking- I was making mac-n-cheese out of a box.
I found a local home brew store and then I was convinced I needed more control of the recipe after I tried steeping a muslin bag with a pound of chocolate malt a William's Double Stout kit. (I was blown away by how much fresher it tasted and how much flavor there was from just stepping some grain along with the kit!)
If I had to do it over again here's the advice I'd give myself to speed up the learning process (and give the most bang for the buck):
1) Book number one that helped me: How to Brew by John Palmer
2) Book number two: Brewing Classic Styles (there is no shame in extract brewing and the book gives all grain versions too should you decide to go AG)
3) Help someone brew AG and watch. (I took a class at the local home brew store since I didn't know anybody.)
4) If you don't have a propane burner, then a turkey frier is great if you are on a budget (about $40 when you find the sale). Even the cheap aluminum pot comes in handy now and then.
As they say in the Ad... "Brewing is easy the William's way", but I get much more satisfaction by brewing MY beer.