I know that some players have been going for a fast Penal Battalion in their opening builds. The idea is to keep them constantly fighting so they get vet quickly. Don't retreat the penals, just merge conscripts into them and retreat the conscripts when needed.
i will expand on this since its the opening i use.
send the engineers to cap the nearest point and retreat them as soon as they cap.
build 2 conscripts.
build 1 penal, observe if they get mg42 and make a scouc car acordingly, else make another penal.
you should have 2 conscripts and 2 penals with an optional scoutcar.
penals should be at the front allways they shred grenadiers, upgrade them with flamers, and only upgrade ATnades in your conscripts, the situations in wich you would use molotov are now handled by the flamer penals,
send your penals to cutoffs and make use of their high damage, keep them reinforced with merge and never reinforce them normaly, your penals are pretty much capping the points penals leave behind and reinforcing them.
later if you feel you have good micro, you can make a sniper or else make a 3rd conscript or another penal, it depends on if your enemy makes more infantry then your army would be 3 penals 2 conscripts, if he makes light vehicles then its 2 penals 3 conscripts for the at nade potential.
allways keep the presure on, and if they have mgs, remember your engineers with flamers, and flame on, burn the facist
penals are better used at longer range, dont look at the flametrower as a weapon but instead as a tool, its a treanch clearer, an assault disencourageer, and a tool to finish off weakened enemies, penals are pretty much glass canons and should be used with care. in due time with trial an error you will lean in wich situations you can asault and wich situations you should just stand back and shoot from far.