My main strategy is just to be as denfensive as all get-out. When I win (which isn't always), it's usually by attrition alone. Objectives are just a bonus.
I have a saying for my hobby; The safest unit is an unspotted unit. My opponents will have much more trouble trying to defeat an enemy they cannot see. Ideal situation: you want your spotters to see his entire force, whilst all the enemy can see is your spotters.
Again, make sure your units are unspotted, keep expendable units out in front to spot. Protect light armor at all cost, along with HQ's, loaded units, and artillery.
Wear out the binoculars button when plotting a route of travel. You must know what hexes can see, and be seen from various points. Important: be sure to do this before an armored unit moves into it's final destination hex (click on the binoculars button and then click on the desired hex, *before* your unit moves into it, to get an idea of what can see the hex. Be aware that unspotted enemy units might be in visual range of this hex).
Game winning tip: Have a plan of action - where do you intend to be in 5 turns? In 10? By the end of the game? And what will it take to get there? :chin:
Read the manual. I cannot stress this enough. I even re-read my manual occasionally.
Security. Never allow the enemy to flank you, or break through to your "soft" areas. Best way to help prevent this disaster - put spotters on hilltops, put infantry on crucial road junctions. Back up the infantry with an AT gun if possible.
Attack (and defend) from good terrain. Forest is your friend. Vehicular-class units (includes mortorcycles, wagons, horses, and bicycles) need to avoid bunkers, trenches, and pillboxes (they get no benefit from them), all units need to avoid ending their turn in open terrain.
The map. At the beginning of turn one, study it very carefully. Locate the hilltops, the river crossings, possible bridges you can destroy, etc. Use the "rotate map" feature if you need to. Failing to note the particulars of the map can cost you a game.
Talk your time on a turn. If you are rushed, stressed, or sleepy, come back to it and play later. Never play when you aren't at your personal best.
P.S. Players with lower win percentages actually get more medals/recognition than other players, because they are seen as having extra "gumption" and an increased ability to handle severe adversity. Click on a higher ranked player with a lower win % and check out all the shiny medals... :)
Just my 2 cents. And don't take it personally - wargaming is just a goofy hobby we play - it's just a diversion. Peace.