Dr. Neptune 
Loosen the strap slightly, lift and reseat the skirt, then clear hair or hood material from the sealing edge. Most mask leaks come from fit, strap tension, facial hair, or a damaged silicone skirt rather than a mask that needs replacing.
Rinse your wetsuit in fresh water, dry it fully inside and out, then store it flat or on a broad wetsuit hanger in a cool, dark, dry place. Avoid thin hangers, direct sun, heat, tight folds, and sealed storage while the neoprene is damp.
Rinse your regulator with fresh water as soon as practical, keep the first-stage inlet dry, and never press the purge button when the system is unpressurized. A careful home rinse and dry prevents salt buildup without risking water inside the hoses or second stages.
For most recreational divers who make warm-water single-tank dives and travel occasionally, an aluminum 80 is the easiest first tank to own. Steel wins for regular cold-water or drysuit diving, where its negative buoyancy and compact size can improve trim and reduce carried lead.
For most recreational divers, open-circuit scuba is the better choice because it is simpler, cheaper to own and travel with, and supported by far more operators. A closed-circuit rebreather makes sense when long runtimes, quiet approaches, or deeper technical objectives justify its higher cost, training, maintenance, and bailout demands.
Most beginner divers should use a simple, reliable dive computer after learning how to plan and back up dives with tables. Tables still win for entry-level training, understanding decompression basics, and handling a computer failure.
For most recreational divers making regular dives in water around 60°F/16°C or colder, a drysuit is the better choice because it gives you adjustable insulation and leaves you warmer after the dive. A wetsuit still wins for warmer water, short dives, occasional travel, and divers who want simpler, lower-cost exposure protection.
For most new scuba divers, a medium-soft paddle fin is the better first purchase because it builds useful kicking control and works across more dive conditions. Split fins are the better pick when low-effort cruising and reduced leg strain matter more than precise power in current.
For most recreational divers doing repeated dives at moderate depths, nitrox is the better choice after proper certification because it reduces nitrogen loading. Air remains the better gas for deeper dives, simple one-off dives, and sites where nitrox is unavailable or costly.
For most recreational divers taking warm-water dive trips, a lightweight jacket BCD is the easier travel choice because it packs as one familiar unit and needs less setup. An aluminum backplate and wing wins for divers who want a modular system, consistently good trim, and a configuration they can tune for different diving.