It may seem cliche but if you look after your board, it will look after you, not to mention extending its lifespan.
Keeping it Shady
Avoid leaving it in direct sunlight or places of extreme heat and temperature change. Leaving it out to cook even in a bag will result the weakening of the outer layer or the board could start to crack, in turn leading to water damage, causing delamination over time.
Be careful when leaning your board upright against things, a strong gust of wind or a simple knock could result in a crack or dent in the board which means an expensive repair job will be required. Not to mention time out of the water!
In the Water
Be mindful of where you are surfing, a shallow break could mean the end of your fins and rocky breaks could mean the end of your board! Always be sure to assess the location and conditions before entering the water; for your personal safety and to make sure it is the right spot for your board.
Clean off the Beach
Make sure you rinse your board after every surf as salt water can damage your board over time. You also want any sun cream that might have got on your board to be wiped off as this can also discolour the board.
If your board does receive a ding be sure to get it repaired straight away as over time it will allow for water to seep into the foam core, which makes your board heavier and will effect performance