You'll be amazed at what they pick-up on and what they don't.
But, I wholeheartedly agree with not speaking to them as a baby. You'll have to alter your approach vs. talking to one of your friends, but they're much more perceptive than we know.
Our daughter had to have tubes for the second time a few months ago. She's quite vocal, but she's hard to understand at times. We often have to have her "show us" so we understand her pronunciation of a word. Yesterday, it was umbrella that had me stumped. I finally figured it out, but I had to try for a few minutes very diligently.
Our kids loved doing flash cards. We had some Baby Einstein animal ones that they both still love (we taught our daughter both the animals and how they moved - pretty entertaining), and a cheap set from Target with basic words on it. But, describing everything in the world around you is the easiest way for them to make the connection between words and the objects, colors, emotions, etc. they describe.
Good luck!