personally i would go COLL + EPLL because of how it transistions to ZZLL if you go for that. Once you have COLL down, i feel it's really then just being able to recognize how you're supposed to move the edges around at that point i think (i'm not quite at that point yet so i can't speak for that)
work on block building, it's different to get your head around that because of how free you are really to be moving the R U and L faces around, i'm still getting used to it myself, or at least making my block building more economic and efficient
i've been using ZZ for at least 2 months, still not quite that strong in EOLine planning, but it's more just me being too lazy to actually plan it out and just being content to spot bad edges as i go, i really need to make more of an effort to plan that part out