I'll show you how I built my templar last time around
first 8 levels
resolute technique will help if you use sceptres. if you prefer wands, skip it. I like using totems to cast my spells, if you prefer to cast spells on your own skip that too.
this is an alternate build
for level 32 if you want to skip totems and resolute technique. this will make you tougher vs. melee but you will be short on mana and light on melee damage.
I'm getting in position to get more mana by branching my constellation to the witch section.
just shy of level 60
and then my character got wiped just when I was starting to dominate. I didn't die once between levels 30 and 59.
the most important thing is to get your ducks in a row and get clusters of defensive bonuses. pick up offensive bonuses where you can but they shouldn't be a priority. you should try to make your spells stronger through gem levels and gear.