I'll tell you what I was told about my first time out on the lake.
1) Stay at least 200 ft from any island. If you need to get closer than this, keep a sharp eye out for rocks. Remember they may not be on the surface. I now have my own personal story about this!
2) Use the Bizer chart and check the areas where you will traveling. Look for hazards, markers, no wake zones, etc.
3) Be well aware of the larger hazards around the lake. Of paricular importance are places like "The Witches", that may appear to be a safe wide open area, but is very hazardous as it has rocks lurking just below the surface. Once you know where these major hazards are located, you will do fine, just be aware of #1 mentioned above.
4) As others have said, don't ever follow anyone else, always follow your chart and the markers.
5) Know how to read the various navigation markers, and if needed (if you are not comfortable reading the sky to know North, East, South or West), have a compass on board to know which way to pass any particular marker.