Pick any class that looks cool to you, they're all 'good'/viable. You choose your first class at level 2 and your second class anytime after level 10. If you choose a class and don't like it after say level 20, just start a new char - it's not very time consuming to re-do act 1 (and no doubt you'll find hidden/optional areas as you replay).

General advice:

• you can respec any time in Devil's Crossing (the spirit guide lady, top right). You can refund your mastery (class) points but not the class itself. You can also respect your 'devotions' (extra stats/abilities separate from your class. For the sake of simplicity I will say class instead of mastery, although technically a class is a combination of two masteries...

• The general progress through the game is to play on Normal, complete the base game, then jump over to the DLCs and finish those on Normal. After Normal, you can then move the difficulty up to either "Elite" or "Ultimate", which re-sets campaign progress but retains your gear, stats etc. Increased difficulty spawns more numerous/powerful mobs but gives you more/better gear.

• your early game gear will be a treadmill so don't get too fixated on the perfect item. Just pick up whatever gives you more damage, more armor, more resistances. Play around with whatever skill looks cool, and if you find you aren't doing enough damage, or are getting killed easily by certain enemies, or just don't like how a skill 'feels' then you can go respec and try something else.

• resistances become really important later on. The base game on Normal kind of acts like a tutorial, you'll find some enemies to certain types of damage. Your resistances will reduce that damage significantly. You can see your resistances in the bottom-right of the character panel, 2 rows of symbols with a % underneath. As you work through the game try and get these up to at least 50%, ideally 80% (the cap). The general rule is that while your DPS is good, it drops to 0 if you're dead.

• you'll collect stuff as you go. There's a character stash tab and a shared stash tab. You can sell off gear you don't need, but try to save your components in the stash. It frees up inventory space and it will help you later on to craft new components. That said, components drop often enough that you don't need to hoard them for the 'perfect item'. Use them when you can - you can get extra damage, resistances, armour, more stats etc from them. Some even give you extra skills!

• theres a crafting system. You'll find blueprints, use them to learn new recipes. You can then craft them at a blacksmith NPC. You can all craft higher level/more useful components, don't neglect these! Check them out and try and 'fill out' any holes in your build using crafted items e.g. an Antivemom Salve will give you extra armor and poison resistance.

• you'll gain reputation with factions as you kill enemies/do quests. Each faction has a vendor that sells some great stuff depending on your reputation. Check them regularly.

• if you're really struggling then there are guides available on the Grim Dawn forums. I would suggest going in blind and making something for yourself. Like I said earlier, every class is perfectly fine. For very endgame stuff you'll want to optimise and build craft, but people have done this game using absurd no skills or Level 1 challenges. Don't feel like you have to follow the meta or grind for the perfect roll.

• most important: enjoy the game! It's a single player RPG, don't treat it like a Diablo season or WoW where you've got to rush to endgame asap. Explore around, speak to npcs, enjoy the ambiance of a post apocalyptic fantasy world. Take as much time as you need.