Got Meindl Woodwalker/Waldorfer, (so suede is on the inside). But care for either, (suede in or out) is broadly similar.
Suede Outer
Remove laces and allow to dry away from direct heat sources. Then remove dirt with a stiff non-wire brush. If there's areas of heavy soiling, then wet the area and brush off. Finally, waterproof with spray.
Suede Outer Quick Method
Ignore the suede and resign yourself to the fact your boots won't look that good again. But will still wear just as well... and be cheaper to proof.
Remove laces, then remove dirt with a stiff non-wire brush and warm water or cold if you can't be bothered. Allow to dry away from direct heat sources. *Shed a tear for the iminent demise of that soft brushed look. Then waterproof with a good wax and allow to dry away from direct heat sources.
*Alternate finish - stick with spray proofing instead of wax. More expensive but you get to keep soft brushed look for a while longer.
Suede Outer Very Quick Method
Utilise puddles and shallow streams wherever possible. (This method tends to prematurely wear the sole.) Occasionally remove laces, brush over and proof with whatever your have leftover.
Leather Outer
Remove laces, then remove soiling with warm/cold water and stiff non-wire brush. Depending in wax type or spray; either allow to dry and proof or proof while still damp, then allow to dry away from direct sources of heat.
Leather Outer Quick Method
Don't remove laces. Instead, loosen lacing and either shake boot upside down to remove most trapped chip/loose soiling, (to remove all trapped chip/loose soiling, vacuum them out). Remove soiling from rest of boots with non-wire brush and warm/cold water. Depending on wax, (spray if preferred) type, allow to dry or not before proofing the best you can between laces.
Notes. Re-lacing boots before work is the way forward. Or up if that's your thing.
If you're that worried about heavy soiling. What are doing in the forest/urban areas?
If you've read thus far. Now is a good time to:
•Forget boot care and go to the pub.
•Forget boot care and get back to work.
•Go clean those boots.
•Utter the words, "Sheesh" and "I can't be doing with that lot." And either, go to the pub/get back to work/look for the nearest puddle, stream or lake/then clean your boots
•Look down at your feet and wonder why you're reading this, when work footwear are normally ballet pumps.