Pedals -- What *exactly* am I shopping for?

Before getting my Specialized Dolce for my birthday in July, my last road bike was a Huffy 10-speed that was pink and purple. It has also been about 8 years since I last rode a bike, so I'm a little new to this type of cycling.

I'm still using the pedals I got from the bike shop. I have been slowly getting my balance and confidence back and I think I'll be ready for clipless pedals this spring. As I am researching, I have no clue what I am supposed to be looking for in order to compare systems. Any advice for a newbie?

It depends. Do you want to be able to walk in the shoes? Or do you want efficient power transfer and lightness? You can get decent MTB pedals for less, I think, than you can get decent road pedals. (SPD-SLs are expensive!) The downside is that the contact area for MTB pedals tends to be much smaller, so the potential for developing hot spots on your feet is far greater.

I started with SPDs, and they were fine for a long time. At first I had some knee pain, but after a fitting to make sure the cleats were positioned right on my shoes they were okay and I had no complaints for several years.

However eventually the knee problems came back, and then when I got a new bike they were worse, so on the advice of the fitter at the LBS I switched to Speedplays (not sure of the specific model -- X-somethings). They have more float and my knees are much better with them.

The only downside I find with the Speedplays is that it's very hard to clip in and out if dirt gets in the cleats. I bought some cleat covers (plastic covers that snap on) and bring them with me whenever I ride so I can use them if I need to walk anywhere. It's a bit inconvenient, but better than painful knees.

I had similar experiences with SPDs. I like the pedals (durable, easy to get in and out of, walkable shoes), but my knees don't like them. I had some knee pain on longer rides. My fitter tweaked the cleats, and my knees were better, but not perfect. I'm on the hunt for new pedals. My fitter suggested SPD-SLs or Speedplays. I'm leaning toward SPD-SLs because of the dirt issue that ny biker mentioned. The downside is the cost. Even the 105s are pretty spendy.