I've found that lube is THE key element. I get the suit wet, then squirt liquid soap or conditioner inside, flop the suit around to ensure the lube is spread evenly on all interior surfaces, then fold it (the top of the two-piece suit) back on itself and insert my arms into the suit, one at a time...no problems doing that. Then I pull the suit over my head, pop head into hood portion, fold the suit down and pull over the "john" bottom.
Frankly, my only challenges have been in (sometimes) getting the top portion back OFF again, withouth help, because the lube slowly gets diluted and most runs out of the suit while diving/swimming, so I sometimes need to squirt a bit more lube back into strategic spots, then peel the bottom up and flop the beaver tail up from the back so I can grab it from behind my head. That gives me just enough leverage to get the suit started back in the "off" direction, and once it's moving, it comes of okay.
BTW, the plastic baggie trick is something we've been suggesting to our scuba students for years when they were struggling putting on thick wetsuits and had challenges getting fat hands and feet through the respective openings on suits without zippered wrists/ankles. A pair of shortie nylons (anklets or footies) work well in this regard also.