Before you take off, take time at the dock to inspect your systems and identify what tools you should have, get them and try them out to make sure they fit and will get the job done before you need to depend on them.
RTFM (read the friendly manual) for each system and component. Find out what tools you need to complete required service intervals. Keep a hard copy and PDF version of each manual on board.
Keep your tools in a dry environment. Spray them with corrosion inhibitor and wipe them down quarterly so they don’t rust.
Kit-up specialty tools and store them near the system they will service.
Make a label near the item to identify what size wrench or tool is required (see engine mount photo).
Having the necessary spare parts on board is essential, and make sure you have an appropriate complement of tools to change out spares and handle the most common fixes.