You'll find a variety of loot when playing but most of it isn't necessary to acquire. While you are able to sell items to the town in return, returning to town can become boring and cost you a tiny amount as the Scroll of Town Portal D2R Items. This means that you should be just grabbing more valuable objects. The ones that are exclusive to the class -- wands, sacred globes and scepters, barbarian helmets, scepters and more are worth a shot for rings, amulets, and other objects that add for the class's abilities. Concentrate on getting these instead of bolts and other objects that require lots of space in order to increase your profits and decrease the amount of trips back to town that you must take.
Diablo 2 doesn't have an endgame that one would expect from modern games so you'll eventually spend lots of time on boss battles, where you'll be constantly battling the boss in order to collect higher-quality items. However, even before you reach this point, you might be struggling, and you'll be looking to grind XP (and possibly earn useful things) by repeating certain parts that the game offers. Tristram The Countess Catacombs in Act 1 and the tombs of Act 2 Act 3's council and many more are great terrain for earning XP much more rapidly than you would normally so be prepared to make the rounds many times.
As mentioned above the ability of the Necromancer in summoning allies a great benefit to keep some stress off your shoulders. There's no reason not to ask for assistance without having to engage in multiplayer. When you've completed the initial Act 1 story, you'll have the opportunity to recruit your first mercenary through Kashya (one among the NPCs of Act 1's Act 1 town, the Rogue Encampment). There are many types of mercenaries available to buy D2R Ladder Items employ as you move through the game beginning with the bow-wielding Rogues in Act 1.