As you can tell from the summary, this is a build that utilizes the simplicity, yet generosity of the starting Knight class. The biggest thing in Dark Souls 3 is that armor sets don't really differ much besides the weight, and fashion, as most of the sets have very similar defenses, and the Knight Set is actually one of the most defensive sets in the game. This build takes advantage of that while minimizing your wardrobe hunting if you don't care for fashion and like simplicity.
Just because it's a starting set, doesn't mean it isn't great for the long term! It has great defenses, manageable weight, decent poise, and it has a simplistic fashion about it.
Chloranthy Ring +2
Ring of Steel Protection +2
Speckled Stoneplate Ring +1
Life Ring +3
Stamina regeneration is key to survival, the rings will boost physical and elemental defenses, and you can always enjoy more HP.
Right Hand Slots:
Refined Longsword +10
The Longsword, despite being common, is an exceptional straight sword due to it's damage and moveset. When refined, the damage makes it nearly unrivaled.
Every self-respecting melee fighter should have a backup option; A bow like the Longbow is a good option. Poison Arrows are recommended for tougher enemies.
Left Hand Slots:
Knight Shield +10
The Knight Shield may be basic, but it's still a good shield for blocking most attacks.
Keeping a torch on hand is very important for dark areas, but more important, those dreaded worms that cause blood loss.
Hot Bar Items:
Green Blossom / Budding Green Blossom
Blooming Purple Moss Clump
White Sign Soapstone
Homeward Bone / Coiled Sword Fragment
The hot bar items speak for themselves. Any resin will work based on the weakness of the enemy you're about to fight, particularly bosses.
Warriors of Sunlight
Who doesn't want a little bit of Jolly Co-operation?!
PRAISE THE SUN!!