This answer depends almost entirely on what kind of deck you have. If you have a concrete deck, you can never go wrong with a solid pressure wash. Those things are awesome. Not only because it blows away debris, but it will destroy things like algae that lead to slippage and breakage. Using the right kind of sealant will go a long way. And remember to repair small cracks before they become big ones!
Wooden decks are more complicated. You have to make sure you sweep it, shovel it (weather permitting), seal it often, clean up grease spills (from the grill) immediately. It’s a bit more high-maintenance, so keep that in mind if you’re deciding what kind of deck to have installed.