This is a fairly open ended question, so our answer will be loose.
Before anything else, learn how to turn off the water to your home. Learn how to turn the supply off at the meter and ensure your have a tool handy to do so, in the event that you have a pipe burst.
If you mean water infiltration damage, as in water coming into a home from the outside, then it is essential that you inspect the most common problem areas. These areas include from the top of home to the bottom - plumbing vent pipes or other roofing penetrations, chimney flashings, house flashings, and gutters. When addressing gutters, you want to know whether or not your valleys have been properly addressed, whether or not your home has drip edge installed, your gutter connections, and gutter seams. You want to ensure that your gutters have been cleaned (and are not clogged), check the soffit/eave construction and condition, the siding and window flashing, and know whether or not your windows were installed with window tape that was applied in weatherboard fashion. Check deck-to-house connections done with flashing to see if it has been properly lapped and is intersecting with siding, exterior door thresholds, ground grading away from house. Inspect the general grade of your lot and determine whether or not it handles heavy rain and doesn’t pool water near your home. Make sure that there is drainage installed near the foundation/footing and that there is water-proofing on foundation walls.
Water damage on the interior of the home may be caused by a lot of items as well. Many of them can be considered and addressed before anything bad happened. The items to look for in the interior of a home that could contribute to water damage include: condensation pans/pumps/drains for HVAC systems in attics, condensation around vent pipes in attic, improperly insulated HVAC duct lines or register boots in attics, unvented bathrooms with showers, shower pans and thresholds, plumbing fixtures in showers, leaky supply lines under vanity cabinets or behind toilets, toilets that are prone to clogging and overflow, old rubber supply lines to washing machines or dishwashers, refrigerator supply lines, ice maker drains, and in general, water supply lines.
Regularly inspect your home. If you find a problem, fix it immediately. When it comes to water, do not attempt easy or patch-work repairs. Fix it early, fix it right, and reinspect it soon after completing any repairs to ensure you actually repaired the entire problem. Water and Time are common forces that are the most destructive in any home. If a problem isn’t addressed, or if you only halfway repair it, you end of with those forces working together to damage your home.
Preemptive actions you can take include: get your plumbing supply lines insulated properly to prevent freezing and bursting. Have a licensed HVAC contractor inspect your system and ensure condensation pans/pumps/drains are all working properly and that all the duct work is insulated so as to prevent condensation build up. Have your crawlspace/basement checked for moisture and consider encapsulating your crawlspace (particularly if you live in the southeast) or sealing your basement walls with a system that has a lifetime warranty. Upgrade all your supply lines for your toilets, sinks, and washing machine to stainless steel hoses. Upgrade all of your supply-cut offs from the older turn models to quality 1/4 turn valves. If/when you remodel your showers, make sure you have your shower pan and drain flood tested prior to tile being installed, make sure you install quality plumbing valves purchased from a plumbing supply house, make sure that the plumbing fixtures are not installed on exterior walls, and tell your plumber to go ahead and install cut-off valves while the work is taking place, for future ease of work or in need of emergencies. Regularly inspect your home visually yourself and consider a Home Asset Management company to inspect your home twice a year.