you can get a legend that explains all lines and symbols on topo maps, usually from the map dealer where you buy them or write to the government agency that sells them. I just received a topo index for Wyoming. they are great maps.
It depends on what country and game you're looking at hunting. In my case i hunt alot of high mountain country for mule deer so i look for steep inacessable country as far from any roads or trails as possible. I'm sure if you hunted the low country there would be a number of different signs to look for. Where ever you end up hunting it's always good to find the nearest water sources as well.
I am after high country mule deer and thanks for the information. I haven't really used topo maps much, but I have cabin fever so bad this year I'm trying to scout on my computer. Can't wait till the snow melts!