What kind of equipment is it? What kind of shop class is it?
I'm going to assume either metal or wood.
Many ideas are similar, but fire is a big concern in metal shop that would be unlikely in a wood shop.
Things in common:
Protect your hearing (this is often most overlooked)
Protect your eyes AND face
Get very used to doing things in a way such that if something goes wrong, you don't get injured (example you use a knife and cut away from yourself so you don't get cut if it slips).
Understand proper use of all machinery. If you don't know how to use it, get instruction from someone who does.
Understand proper use and storage of all chemicals
Do not interrupt or divert the attention of someone else who is using any dangerous tool.
Secure your material. Many hand injuries result from failure to do this.
Keep tools in proper working order. A dull knife is more likely to cause injury than a sharp one.
Use the right tool for the right job, including such things as push sticks and clamps.
Think before you act.
If you are tired or distracted, stay away from all dangerous tools and equipment.
Protect your lungs
Be careful not to put things in a dangerous place (hammer on top of a ladder or knife near the edge of a table)
How important is all this? Consider that a table saw in a wood shop can cut your arm completely off BEFORE you feel anything.
Given the choice between protecting you body and protecting your project, protect your body.