The first plant/rocks to get rid of are any that you have more than one stack of (sell the excess).
In D2:ED I put 3 or 4 points into encumbrance before I got the battle tower (playing a warrior I had a few to spare), since you can reskill once you get it, and recover those skill points. Once DKS is out on Xbox here I will not bother with it for my next character, since I will have a better idea of what I need to keep.
In D2:ED I kept a few pieces of equipment that were ok, thinking they might be good once I had access to better enchantments, but by the time that happened there was better equipment around with just as many enchantment slots. I didn't use one item that I kept because it had extra charm or enchantment slots compared to other equipment available at that point.