The first rule of any signalling or communication devise is to preserve power unless it is likely or known that somebody is listening or visible to you. It's a good idea to keep a running internal dialog of major cross streets, bridges and landmarks as you pass. example " we just left the original Col Sanders restaurant and the pecan pie is o.k. and I can see a split rail fence with Saddlebreds running along the ditch I'm in. You might consider one of the compressed gas boat horns popular at sporting events. If you have cracked ribs you won't be yelling for help and if your camoflaged by a big old shagbark it helps searchers. A fat newspaper truly is a cheap investment with multiple uses; insulation, tinder, splints, bandages.