Your first step in starting is to choose a class and it's true that the game does almost nothing to describe the game's characteristics like any other. Apart from a brief description it's up to you to decide depending on the style of the class. You can play additional characters, you can't switch classes once D2R Items you've made your choice. So whatever time you spend in the character will go for no gain if you decide to prefer playing a different. (You can, however, use the brand-new shared loot box that allows you to move objects between characters. No more beginning an adventure, dumping everything you have in the town, exiting the game, only to return with a different character to move things.)
Certain classes are better suited for beginners than others. Sorceress is heavily dependent mana and spellcasting, as one would expect and is also quite weak and weak, which makes it a difficult character to play on your own in the beginning (although her ability to teleport is an absolute lifesaver when you master it). However Paladins are able to take more damage and are able to heal without the use of potions, whereas Necromancers are able to draw in a horde of minion warriors that are not just able to deal destruction, but, more importantly they can distract and absorb enemies' attacks, helping keep your character alive.
From a pure entertainment point of view It's an entirely individual choice, however there's an explanation for why Barbarian was the only returning character from Diablo 3 at launch--Blizzard thought there was a lot of potential for improvement in that one. The lack of information available on the screen to create characters buy d2r items doesn't mention this, however there are a variety of class designs and completely diverse ways to play the character of a particular class.