The excitement can easily wake you up, but as time passes, it should affect you less and less.

The most important thing is to be as fully present in the dream scene as you can. Your mind has to be anchored somewhere, so make sure it's focused on what's around you, and not on what's waiting for you when you wake up.

At the moment I become lucid, I try to remember to just take a good look around and note all the details that are already there in the dream. Notice the temperature, whether there are any smells, sounds, or maybe a breeze in the air. Try to feel the ground under your feet. Take a good long look at your hands and arms, and see what they look like. Touch things with your hands and ask yourself what they feel like.

All of this is very grounding, and can set you up for a nice long lucid if you're in the right frame of mind. I find that my sense of touch is probably the most important to me personally. My lucids that begin with me pausing to touch things are usually the most vivid of all.