This can be dangerous business. That does not mean you must get hurt, but it means you COULD. Always work safely. Taking shortcuts is not expedient, but dangerous.
Consider the typical stage:
The layout constantly changes. Onstage is brilliantly lit but it is poorly lit backstage. In the dark are many hard, pointy objects, lighting booms, scenery, cables to trip on, people in black are rushing about in the dark. The orchestra pit might be floor level or 30 feet deep, w/ no railing. Overhead and offstage are tons of equipment that may spring into motion without notice. In industry, such movements require flashing lights and sirens, but not in theatre.
Consider the work spaces:
The arrangement of spaces changes constantly. Catwalks are 30 to 80 some feet in the air, often with inadequate railings, where we toss 50 lb. weights. Falling sandbags and scenery are stock elements of B movies and Phantom of the Opera; we confront them daily. Our only defense is safe working habits and common sense.
There are many ways to do most jobs on stage, but you should learn how the Local prefers it done; not because it is the "best" way, but because it is the expected way HERE. Surprises cause injuries.
Wear durable work clothes and sturdy boots or shoes for protection. Crushed hands and fingers are common; gloves and care will help. When climbing, use proper fall arrest equipment. Its not just smart, its the law.
The trick is using safe working practices at all times, and avoiding unsafe situations. When lifting, use your legs, not your back. Work together on heavy lifts. On ramps, push from the back and sides of large crates so as not to be run over if you trip.
Occasionally we build or repair scenery, and may be exposed to toxic paints, solvents, or chemicals, or welding fumes. In such cases, you need proper protective gear, ventilation and respirators.
Avoid working while under the influence of drugs or alcohol, including prescribed drugs which could cause drowsiness, lightheadedness, or disorientation. If you DO work under the influence, you WILL be sent home.
If you have problems with any tool or machine, bring it to the attention of the show or venue staff so it may be repaired. Don't just ignore it and don't try to fix it yourself unless directed to do so.
IF YOU DON'T KNOW - ASK! If you feel uncomfortable with any task, in terms of experience or safety or any other reason, the Local WILL back you! Don't let the roadies pressure you into doing something unsafe. There is no such thing as a dumb question, only dumb mistakes and injuries.