How to get into multiplayer

Hello,
How do I get into the multiplayer or Battle.net playstyle? I've tried multiple times, but I can't seem to grasp it. I miss my "/players 8" command and having my maps "saved." I genuinely don't know how to farm in this constantly changing online environment, let alone trade effectively. It feels a bit overwhelming, even though it's such an old game, so I'd appreciate some tips on all these aspects.

In multiplayer D2, how do I farm, level up effectively (including the early grind and joining "baalrun 32-33-34-35..."), trade properly, and most importantly, have fun?

If playing online isn't fun for you, then just... don't.

All point's you mentioned are valid - farming is more tedious, so you need to learn map layouts for having any chance of keeping your sanity and not just running around in random directions. Also, items that have any value in trade are few and far between, and you have limited number of online chars. If you don't have buddies you can play with regularly, then just stick to offline, if that's what gives you fun.