You'll want to bring along line plots and/or copies of drafted maps from previous sessions in order to easily see where to go next.
You should seriously consider using Auriga (
http://www.speleo.qc.ca/Auriga) on a Palm PDA. It's free and you can get inexpensive older Palm models on eBay. If will allow you to see your line plot as you go, help you sketch to scale, identify loop closure errors on the spot, and see the data for the entire cave (to see where you're connecting to). Data can be imported/exported to Compass for loop closure reduction and other work requiring a "real" computer (printing, 3D animation,...).
Make sure to leave permanent stations, and mark them as such in Auriga to help you find them faster when you connect. By writing a note (in Auriga) about the exact location of such a station, you can leave stations with less visual impact.
Chris