Find some guide to follow, for example, this site has some Demon Hunter builds available. With full set you can go into higher Torment levels and also higher Greater Rifts.

Play in season, reach 70 level, complete some season journey challenges - you will be required to play low Torment difficulty levels and will need to complete some beginner levels of Greater Rifts (20-30) - and you will receive a full set for your character as Haedrig's Gift - 3 packs with 2 set items each.But you can view seasonal leaderboards to check what gear top players use - Demon Hunters Leaderboard What builds are the best? Nobody knows, meta changes every season. So you are free to equip any Legendary items, but better results will be if you are stacking items affecting the same skill. They gain bonuses for each Legendary / Ancient item equipped. In contrast with previous, they rely on your character not having any class set items equipped. Legacy of Nightmares (LoN) or Legacy of Dreams (LoD) builds. Once you complete the set, you aim for additional items that affect the same skill or generally improve your character. Sets have some ridiculous modificators to damage of some skills, like 'Skill X now deals 10000% more damage'. Your goal is to complete full set of character specific gear. In current game version there are two types of endgame gear: Top players manage to complete GR150, for novice players - it's good to aim into GR90-100. If you want to play endgame, you will probably want to build your character being able to complete high levels of Greater Rifts. You can complete the game with any items. If you just want to play main story, don't bother looking for the best gear.

Diablo 3 season 20 demon hunter