Never add new electrolyte (battery acid), use distilled water.
Don’t use unregulated high output battery charges to charge batteries, especially AGM and Gel batteries.
Don’t put your equipment or toys (jet skis, vintage cars etc) into storage without some form of maintenance charger.
Don’t disconnect battery cables while the engine is running (your battery acts as a filter).
Don’t put off recharging your batteries.
Don’t add tap water, as it may contain minerals that may contaminate the electrolyte.
Don’t discharge the battery any deeper than you possibly have to.
Don’t let a battery get hot to the touch and boil violently when charging.
Don’t mix size and type of batteries.