IMO-penals take too long; if you're gettign penals, just get snipers. Then, make your opponent freak out when his 4 pio squad just got reduced to 2 after some conscript fire and a sniper shot.
Scout cars SHOULDN'T give you trouble with at least 3-4 conscripts. A.) TRYYYYY not to fight it 1conscript v 1 scout car. B.) Try to get some support or back up with anyother kind of unit (not sniper, even thou scoutcar does take small arms dmg).
I have been finding AT nades being researched before molotov in my build too to actually do STOP scout cars/ Half-tracks.
Guards are good, but it tells your opponent: "OK, he went the 1 of the 2 doctrines that have guards in them!". Things i've been finding bad with guards are, they need to sit still to shoot their DP & PTRS guns, which slows down mobility and increase vunerablity. So a well-micro'ed scout car(s) and Half-track(s) can still give some trouble to guards too.
TLDR; get at nade quicker. Don't be afraid of scout cars w/AT nades. Focus on paying attention to your units. Make sure they are not idle (shift-click is your friend).
Getting two snipers is excessive early on. You sacrifice a great amount of map control, which is absolutely a major strength of Soviets early on, and will set yourself up for great pain if your snipers ever get caught out in the open by a roving scout car. I don't recommend at all getting a sniper before having at least 3 conscripts on the field to at least screen the sniper from infantry and possible early scout cars.