Fall protection includes nets and safety harnesses, which serve to arrest a fall rather than prevent it. Before working at any elevation, assess the fall protection needs. Choose the personal protective equipment (PPE) that is most appropriate for that particular location and the work you're doing.
Don't get caught up in OSHA height requirements. Fall safety isn't about trying to see how high you can go before you "have to" use fall protection. In some cases, height has nothing to do with it. For example, you may need to work just a few feet above a hot process. It's uncomfortable to work directly above steam pipes, but fall on them and height may not matter much. If you can fall on something that can hurt you, use fall protection regardless of the height.
When planning fall protection, we tend to think of PPE first. But PPE is a last line of defense for fall hazards, so starting there is backward. Begin by assessing the area. What hazards can you remove? For example, can you ensure the surface is dry and free of debris? What about installing a ladder, railing, or guard? After you address how to prevent a fall in the first place, look for ways to catch yourself if you fall.