Endgame Guided Builds
Your Build Is Bad & I Should Feel Bad
(If you're not following one of the recommended Guided Builds, you can skip this section.)
In the interest of simplicity, the Guided Builds included in this guide stayed away from a few things that, if I were making an optimized build, I would never have skipped. At this point you've played through the game, accrued some currency, and have a basic handle on the game's mechanics, which means it's time to revisit your build and make some tweaks.
Tipping The Scales
Depending on the quality of your equipment, different modifiers and support gems will have different power levels. If, for example, your weapon is very bad, Added Damage modifiers are much better than they will be once your weapon is very good.
The Guided Builds are built around the assumption of downright terrible gear. As a result, some of them use support gems that would not be optimal for better-equipped versions of that build. Once you've gained a few items, consider firing up Path of Building and seeing if some alternatives might be better than the support gems suggested as part of the main guide.
In general, expect Added Damage bonuses to become weaker, and crit-related bonuses to become stronger (relative to Increased Damage) the better your gear is.
It's Party Time
Many players play PoE solo - but maybe you don't! The Guided Builds assume solo play so that you won't be dependent on outside help, but that doesn't mean you can't play with a friend.
If you play with friends, consider adapting your build to party play. For example, you may be able to swap out a Curse for one that is slightly weaker for you but much stronger for your party members - perhaps you use Cold Projectiles and your party member uses Fire Projectiles, so you switch from Frostbite (which reduces Cold Resistance) to Projectile Weakness (which increases Projectile Damage).