Keep your people, and yourself, busy. Despair may be your worst enemy. Your group should learn how to use weapons effectively. Safety, maintenance, handling malfunctions, and marksmanship are all of equal importance in a survival context. Because this is an area where mistakes can be fatal, instruction should be sought from qualified professionals, such as the National Rifle Association.
Tactics are another important area of study.
Learn how best to utilize your weapons under various conditions and environments, such as snow, rain, or at night. There are several reputedly good schools for this type of study. There are also many books such as military manuals which can be of help, if accompanied by lots of practice. Study first aid diligently, as this is one of the most essential areas of self help study. The American Red Cross has excellent, inexpensive courses on CPR and basic and advanced first aid.