I could really use some tips and/or a discussion on how to play marginal hands like ATo and AJo preflop.

This is pretty much how I play them in general right now:

EP - I limp with AJ, fold AT, fold to any real raise.

MP - Sometimes I open-raise, sometimes I open-limp. If the pot has been raised, I fold, if someone has open-limped I limp behind.

LP - Always open-raise. Fold if it's been raised, limp behind if there are limpers.

Several parts of these plays feel questionable. Raising with it in LP means I will only get called by better Aces, but limping with it seems weak and I want a chance to pick up the blinds. Limping behind with them also seems less than optimal, since they don't perform very well in multiway pots unless suited.

EP- seems fine but I sometimes fold AJ if the table is aggressive and there are alot of preflop raises.

MP- Fine also

LP- For me, raising depends on who is on the button and in the blinds. If they call raises with QT, A9 and things like that then I raise. If they dont call raises enough, then I raise and take the blinds. If they are somewhere in between then I limp.

Looks okay. I wouldn't recommend limping AJo in EP though, especially when the table is aggressive.

True, if the table is aggressive I might as well fold AJ preflop in the early seats. However, what about late position if...

The pot is unopened
Would it be better to just open-limp instead of trying to steal the blinds? This makes you vulnerable to someone stealing from the button or in the blinds but also decreases the chance of you getting sandbagged by AK/AQ since they will probably raise (and are likely to just cold call if you raise and pop you when you both hit).

The pot is opened
Rasing to limit the field, preferably making it HU? I've done this a few times with varied results but I do feel very vulnerable when raising without proper values like this.