Legendaries you can craft from plans are useless!
The only craftable set of any real value is Cain’s for leveling and the set that gets more Death Breaths to drop. Everything else is trash. They are a complete waste of resources to craft - you are better off rolling a dozen yellows for something perfect.
The items you need cannot be crafted at the blacksmith from plans - the only way you can get them is when they drop out in the wild from killing mobs and bosses and guardians and from cache bounties, gambling with shards at Kadala and using cube recipes to upgrade rares.
Go here and peruse all the legendary items for slots that don’t make up part of your set - typically bracers, amulet, rings, weapons and offhands. You will notice many if them synergise with character specific skills and often those will be skills that also relate to your set. Many of these are mandatory as they will provide damage mitigation in some form or another, proc’d off one of the skills you’ll probably be using with your set.
For example:

These are the bracers you need for a Raiment monk. Raiment boosts damage of primary generator skills, so you will be using them a lot. Luckily, these bracers seem custom designed to give you huge damage reduction!
Now look at the Shenlong set gloves:
A damage boost based on how much primary resource you have? Tailor made for a monk that does damage with primary generators, like the Raiment set - almost like they were designed this way! ;)
What else in there boosts primary skill damage? How about these:

Dayum, I want me some of those! But, how can I use them if I have to wear the Raiment pants to get the set bonus. Cube them to use that legendary ability without having to actually wear them.
And so it is with D3 - your build decisions have ultimately been made for you by the devs in how they have designed these item synergies - at least if you want to progress to TX and beyond. For the most part, anyway.
Now items! The most affixes that can be rolled on an item is six (excluding a legendary bonus) - four primaries and two secondaries.
Primary affixes are - main stat (eg Dex), Vitality, All Resist, Armour, Life%, Crit hit Chance, Crit Hit Damage, Cooldown reduction, Resource cost reduction, Sockets, Weapon Damage, Area Damage, Elemental Damage (eg Fire), Skill damage bonus (eg Dashing Strike), plus a few others.
Secondary affixes are - Gold pickup bonus or radius bonus, Monster XP bonus, Resist specific element (eg poison), Chance to x (blind/stun), thorns, plus a few others.
A few points:
- generally you are only paying close attention to the four primary affixes, secondaries are what they are if the primaries are good.
- Main stat rules - if an item does not have your main stat, it is worthless.
- Sockets rule - any item that can have a socket, must have a socket (chest x3, pants x2, helm, weapon, rings, amulet) -
Your offhand is the only exception. Note legendary gems go in rings and amulets, hence the socket requirement.
- If an item has All Resist as a primary, it cannot have a resistance as a secondary and vice versa. Less of an issue for monks because they will run the Harmony passive (you are running the Harmony passive, aren’t you?)
- Crit rules - if an item can have crit on it, you want crit on it. If it can have both crits on it, you want both crits on it.
These items are mitigation peices, shit that keeps you alive - they can’t roll crit, so generally stack them with life, armour, etc.
- Shoulders
- Chest
- Pants
- Boots
- Belt
These items are damage items, shit that kills shit. They can be rolled with crit on them and so generally you want them with crit:
- Hands - dual crit
- Bracers - crit chance
- Offhand - crit chance
- Amulet - dual crit
- Rings - dual crit
So, you can begin to see your ideal affix options, per item, narrow quite substantially. For example, generally a perfect ring has to have as it’s four primary affixes, in order of importance:
- socket.
- main stat
- crit chance
- crit damage
A perfect chest piece would be something like:
- main stat
- vit
- sockets
- All Resist, life %, armour, maybe skill damage
Tons of affixes in D3 sadly have no use. Outside of Crusaders, thorns is useless. Gold find - meh. Some secondaries are nice to have (reduce control impairing effects), but not at the expense of not having the primary affixes right. It’s about now you stop paying attention to the tooltip that tells you if an item is better than the one you have equipped and instead just start looking for the affixes you need.
So how do you get these items? Run bounties for drops and bounty caches, run rifts for drops, spend your blood shards with Kadala and upgrade yellows to legendaries using the cube recipe. Target the item you think you need to solve your current problem - eg if you can’t take the damage at the moment, upgrade yellow bracers and spend shards on bracers until you get the Spirit Guards.
Crafting yellows is dirt cheap. While waiting for those Spirit Guards to drop, make sure you have a near perfect yellow by crafting a dozen or so at the blacksmith and choosing one with main stat, vit, crit chance and an elemental damage that suits your build.
Remember that you can re-roll one affix at the mystic. This will almost always be a primary affix. Primary affixes can be replaced with another primary affix. Secondaries with another secondaries. It won’t take you long to get the gist of what affixes can be swapped for what. Just don’t make the mistake I made the other night an ruin a decent legendary ring by faffing the re-roll and accidentally choosing a secondary affix when I was trying to re-roll for crit. /facepalm
So on any item, you are generally looking for three good affixes out of the four primaries, with a view to using the mystic to swap the fourth away from something undesired. This is also why yellows are good to get you going - they are cheap to re-roll. Re-rolling an affix on any legendary or set item will cost you Forgotten Souls, which are a rare drop or are gained by breaking down other legendaries at the blacksmith.
Good luck!