A good guide to always remember is - Look After Your Footwear and Your Footwear Will Look After You.
The same can be said with all of your PPE - your foot protection can only take so much abuse before it fails.
Therefore, the best thing to do is protect your footwear like it protects you.
Boots or Shoes will last much longer too, saving you money in the long-run providing .....
1) If they get muddy, clean them.
2) If they are wet, dry them naturally.
3) Use laces properly (don't slip them on and off and stretch them).
4) Store them carefully, don't let them rattle around in the back of your van.
5) Treat your leather safety boots to some saddle soap to maintain durability.
6) And most importantly, if you have an incident where the protection level may have been compromised, CHECK your footwear thoroughly for any failures. If in any doubt, replace them immediately.

To make things easier, we have kept the boots into their specific safety categories.

SB : Safety Basic - This is the basic standard for safety footwear and must have toe protection that can withstand a 200 Joule impact.
SBP : This is the same as the basic standard for safety footwear but includes a mid-sole plate (steel or composite) to protect the foot against penetration.
S1 : S1 footwear is anti-static, resistant to fuel oil and features energy absorption at the heel.
S1P : S1P footwear the same as S1 footwear but including a steel or composite plate in the Mid-Sole to protect against penetration from under foot.
S2 : S2 footwear has all the aspects of S1 footwear, but adds prevention of water absorption for the upper. hey are not fully waterproof and should only be thought of as water resistant.
S3 : You will find the same safety elements as contained in S2 but includes a mid-sole plate (steel or composite) to protect the foot against penetration. They are not fully waterproof and should only be thought of as water resistant unless there is an inner waterproof liner which deflects the water from the inside of the boot.
S4 : An S4 boot encompasses the same level of protection as an S1, however it is moulded from a polymer or rubber that makes them completely waterproof and leak-proof. A safety welly would be S4 at the least, and other codes can be added when the boot achieves other safety standards.
S5 : S5 gives you all the safety footwear features of the S4, plus midsole penetration resistance.

As with any safety footwear acidic material and lime (as found in concrete) will expedite footwear failure. If you are working in such materials, we recommend wearing S5 safety wellington boots only (if you are allowed).