Don't concentrate on micro. Your micro will naturally get better as you improve your general gameplay. IMO micro in coh2 is not as important as in other strategy games. You generally want to pay more attention to tactical and macro aspect of the game. Losing a few units on your level should not be a big deal if you outplay your opponent on strategic aspect.
Playing exclusively one faction (OKW in your case) is also a bad idea. You want to be proficient with all factions because that will give you a good idea which units to expect when and adapt accordingly.
Concentrate on your unit positioning and practice putting them in positions where they can deal the most damage. Make sure you have your flanks covered and push engagements you can win. Don't engage in situations where you are outnumbered/clearly unable to win. Try to have your squads/units on field at all times and soft retreat them for heals/repairs. Hard retreat only in dire situations.
Finally, you always want to analyze games, especially your own losses. Watching twitch streams of better players should also give you some advanced insight into general gameplay like build orders, strategic points on different maps and unit production/call in timings. I highly suggest you refrain from balance sections of coh2 related websites because those are full of butthurt crybabies who just bitch about their failures. Learning curve for coh2 is steep but once you get better it is loads of fun.
Goodl luck and have fun!
