I will typically set all my troops to Regular/Fit/Motivated/+0
I will increase the experience level of specialty troops, such as ATGM, MGs, Scouts, etc. This helps not only with accurate but with their spotting and other hidden skills/effects.
If I have the points, I'll always try to push my Tanks up to at least veteran.
If I still have points, I'll upgrade an entire platoon to Veteran, and they will typically become my reserve troops. I'll hold them back, then send them to where ever I need them. Could to exploit a breakthrough or to shore up defence. The problem with using Veteran troops as your first line, is that while those troops will have a better chance to fight their way out of trouble they die just as easy as a regular troop. Obviously, being Vet or above doesn't give extra bullet/explosion resistance, and chances are, the enemy will be waiting for that first bloody exchange.
Of course, if you look at the map and have a great idea for an attack/defence, they by all means, send a small unit of Crack troops as shocktroopers.
As for your English; I understand you completely, I see no problems there. As for rude, lol, don't worry about it. I'm a big boy and understands that sometimes direct speech is a requirement. Either way, I think we're going to be fine.
If you don't mind me asking, what's your native tongue?