Undead Settlement

Your immediate objective here is to locate Yoel, exhaust his dialogue, and accept his services. One benefit of accepting Yoel's services is that you would be able to level up 5 times with him without having to spend souls for each level. Your goal is to level up 5 times with Yoel, working towards having 16 Strength and 13 Dexterity so as to properly wield the Claymore. Light the Undead Settlement bonfire and return to Firelink Shrine. If possible, talk to the Fire Keeper and level up Dexterity to 13.

4. Undead Settlement, Dark Souls III

Follow these steps to get all 5 levels from Yoel:

1. Talk to Yoel and pump 1 point into Strength.
2. Warp to the Undead Settlement bonfire and suicide your character 3 times. The bonfire is conveniently located next to a cliff, which can be used for a quick suicide.
3. Return to Firelink Shrine, talk to Yoel, and pump another point into Strength.
4. Warp to the Undead Settlement bonfire again and suicide your character an extra 6 times until your character looks like beef jerky. This beef-jerky appearance signifies that you have 15 Hollowing points, enough for you to exhaust the remaining 3 levels from Yoel.
5. Return to Firelink Shrine, talk to Yoel, and level up to 16 Strength (if possible). In case you already have 16 Strength, pump the remaining points into Vigor and/or Endurance.
6. Sit at a bonfire, warp back to Firelink Shrine, go to Yoel's location, and you should see his corpse. Near Yoel's corpse is Yuria. Talk to Yuria and exhaust her dialogue. She sells Purging Stones for 4,500 souls each. Consuming a Purging Stone would remove the beef-jerky appearance and reset your Hollowing point to zero.

Now you should be able to wield the Claymore two-handed. If not, farm the Lothric Knights and enemies near Vordt's arena and level up to obtain 16 Strength and 13 Dexterity. The following videos show some farming routes:

Farming souls: High Wall of Lothric pre-Vordt, Dark Souls III

Farming souls: High Wall of Lothric post-Vordt, Dark Souls III

Grab the Blessed Red and White Shield+1 and equip it immediately. While equipped, the shield would slowly regenerate your HP. The higher the upgrade level, the faster the HP regeneration. Don't upgrade the shield yet; concentrate on upgrading your Broadsword and Claymore. Also grab the Caestus, which is much lighter than any shield. Later on, you would be able to infuse the Caestus with a Blessed Gem.

Various tasks must be completed while you're at the Undead Settlement:

1. Grab Loretta's Bone, give it to Greirat, and exhaust his dialogue. Sit at a bonfire, warp back to Firelink Shrine, and you should see Greirat curled up. Talk to him and exhaust his dialogue. Sit at a bonfire again and warp back to Firelink Shrine. Advance Greirat's questline by talking to him again and send him to pillage for the first time. Warp back to Firelink Shrine again and Greirat should have left the Shrine. Be sure to purchase any items you require from Greirat prior to sending him on his first pillage mission.
2. Join the Mound-makers covenant, then defeat Hodrick when he invades you as a purple phantom.
3. Befriend the Giant Archer to receive a Young White Branch. Always have this item in your inventory for the remainder of the playthrough and never place it in storage (unless you know what you're doing). While the Young White Branch is in your inventory, the Giant Archer's arrows would not hit your character.
4. Rescue Irina and initiate her and Eygon's questlines. You must first grab the Mortician's Ashes, give the ashes to the Shrine Handmaid, and purchase the Grave Key from her.
5. Rescue Cornyx and accept his services. Return to Firelink Shrine and exhaust his dialogue.
6. Help Siegward to defeat a Fire Demon. First, exhaust Siegward's dialogue, then fight the demon. After a while, Siegward would rush in to fight as well. Be careful not to hit Siegward and ensure he survives the fight. Afterwards, exhaust Siegward's dialogue to advance his questline. Also talk to him while he's asleep.
7. Grab the Chloranthy Ring+0 and equip it immediately.
8. Grab an Estus Shard and an Undead Bone Shard to upgrade your Estus Flask.

The area boss is Greatwood, who is weak against fire. Buff your melee weapon with Charcoal Pine Resin or Charcoal Pine Bundle. In case you need an extra couple of levels before fighting Greatwood, use the farming route shown in the next video.

Farming souls: Undead Settlement, Dark Souls III

Once Greatwood is defeated, Greirat should return to Firelink Shrine and his stock of wares now compasses many more useful items. You should have also received the Transposing Kiln from Greatwood's defeat. Give the Kiln to Ludleth and he would be able to transform boss souls into weapons.