This guide is separated into 2 main sections: leveling normally and power leveling. For these guides, we’ll assume that you’re in a 4 man group. If you solo level, you’ll be doing the same things, just more slowly. With this knowledge, you should be fully geared within 1-6 hours of hitting 70 depending on RNG or your free set.
With normal leveling, you’ll hit 70 in 2-4 hours depending on what leveling plan you take. Once you hit 70, your first goal is to get the 6 piece bonus as fast as possible, all while doing everything in a group if you can. Once you get your 6 piece, you should be ready for T6 speeds at the very least. You want to be clearing Nephalem Rifts at difficulties which you can do fast in respect to your build. This is usually sub 5 with a makeshift build or ~2 mins with an actual speed build. For Greater Rifts, you should move it up a little bit higher to get more value from your keys. For example, as soon as we got our 6 piece, my group started doing T7 speeds, but did GR 35+s (T8) with our keys, gradually increasing the difficulty as we got more gear. With this, you should gradually get all the gear you need for your speed build or push build depending on what your group is aiming to do.
If you decide to power level, you’ll hit 70 in 5-30 mins - depending on if you have a proper booster or not (just look for a lightning wiz). If you want to get the rest of your gear through your own means, you can follow the Normal Leveling instructions above for gearing. However, you’ll want to craft/spend blood shards for some level 70 armor and a 2 handed weapon before going out.
If you opt to leech after you finish power leveling, ignore your 6 piece and just hop in Nephalem Rifts to get keys. Make sure to follow your carry closely so you don’t die, and be sure to pick up any good drops for mats. I recommend putting a vit gem on your helm and diamonds on your armor for survivability. All your spells should be for mobility/damage reduction since your damage is meaningless while you are getting carried. Once you have a good amount of keys, ask your carry to spam Greater Rifts for you, as you can just stay at the door since only the boss drops loot. In addition, more legendaries tend to drop in Greater Rifts, so you’ll get the gear you need faster.
Whether you choose to level normally or level through getting a boost, the biggest factor to getting up and running (if not leeching) is game knowledge. Knowing what difficulty you can do with your current gear and what you’re able to farm will get you up to speed faster than aimlessly picking up loot and gambling shards. If you have a build in mind, your gearing process will speed up significantly when you know what pieces of gear you are missing and what to gamble for. (Note: you should only upgrade rares for your weapons unless you are just missing one piece of the build.)
The next thing that will speed up your gearing is knowing how to build around what you currently have - or if it’s even worth building around at all. The only way you can do this is by playing the game and figuring out what legendaries are useable and what legendaries are just stat sticks. If you are new or casual and have no idea of what to do, I would suggest looking over some builds on the site and choosing one that you think you’ll enjoy. Doing this will also give you a decent grasp of what legendaries are good and which legendaries aren’t.