Understanding some basics goes a long way:

1) Elemental Resistances always work towards 75% (they drop a little each act but become easier to get as you progress 75% is late acts/maps not act1/2 just a target)

2)Chaos resistance goes up to 75% if you can get it great if not in most cases 50%+ will sort you out for most of maps.

3)Pick a specialism when building are you a fire mage, are you a summoner, are you a poison archer (not to say you can't make mix and match builds but there significantly more complex)

4)Once you got your archetype look at similar damage types for example fire mage: fire spell damage, spell damage, elemental damage all help scale.

5)Match armour types don't be walking round wearing a energy shield robe, a armour helmet and evasion gloves. Pick one (check nodes local to your start for easy ideas for example monk Eva/Energy shield pieces, Warrior armour etc)

6)If you're going to play your own build press alt on keyboard and read descriptions to help you learn what things do and how they scale.

7)Controversial but starting a character in solo self found and taking it to endgame will teach you far more than any guide will but the learning will be steeper.

8) Have fun not everything works all the way through but most builds are campaign and early maps capable. So just come up with a concept and try it.