Painted World of Ariandel
There isn't anything else worth collecting in the Painted World of Ariandel. You should have already grabbed the Titanite Slab that is accessible by climbing two steep ladders. Two other slabs can be obtained by defeating Sister Friede. One slab is deposited into your inventory once you have survived the second phase of the fight against Friede. The other slab is obtained by defeating Friede and exhaust the dialogue of the Forlorn Corvian, who can be seen sitting when you first saw him near the Corvian Settlement bonfire.
Champion's Gravetender and Gravetender Greatwolf
SL1 Cheese Gravetender and Greatwolf, Dark Souls III
This is a gank battle that is not worth fighting at SL1. During the first phase, you must face four enemies at once: three wolves and the Champion's Gravetender, all of whom are fast. Get the Gravetender down to about half health and the second phase would begin, where you must now face the Gravetender himself as well as the Greatwolf. The Greatwolf is unusually fast for its massive size. Overall, this gank fight feels more like artificial difficulty than a fair challenge. I would recommend you to cheese them from outside the fog wall.
Friede and Father Ariandel
SL1 Friede and Father Ariandel, Dark Souls III
A gank fight that is more of a fair challenge than the fight against Gravetender and Greatwolf. Whereas the fights against Pontiff Sulyvahn and Champion Gundyr are parry simulators, the fight against Friede is a backstab simulator. Use a Dagger+10 that has been infused with a Fire Gem to output high backstab damage and equip the Hornet Ring for bonus damage. Equip the Scholar Ring to allow you to perform the weapon art of the Storyteller's Staff. Prepare at least 40 Throwing Knives. You do not need any buffs for the Raw Broadsword+10 because most of your damage output is from the Fire Dagger+10. For some extra damage output, have some Charcoal/Gold Pine Bundles ready.
The first phase is you against Sister Friede. Friede has a fast sidestep and can quickly close the gap between you and herself. Throw a few Throwing Knives at Friede to help you keep track of her whenever she becomes invisible. You have at least two windows to backstab Friede. The first window is when she jumps in the air and performs an overhead attack. Maintain a fair distance from Friede to bait this jump attack. Dash towards her and roll to avoid the attack, positioning your character behind Friede, wait for the ice on the ground to explode, and backstab Friede. Switch to the Raw Broadsword+10 and get in R1 x 2. The second window for a backstab is whenever Friede becomes invisible. You should have thrown a few Throwing Knives at Friede. The Throwing Knives stuck in her body help you to keep track of Friede whenever she is invisible. Locate Friede, position your character at Friede's right hip, and backstab. Switch to the Raw Broadsword+10 and get in R1 x 2.
The second phase is the easiest because you would mostly run away from Friede and Father Ariandel, both of whom share the same HP bar. Friede is mostly passive during this phase while Ariandel tries to chase you. At the start of the second phase, sprint towards Ariandel from your left while avoiding Friede. Bait Ariandel into dashing towards the top-left corner of the arena (top-left from when you first enter the arena), then perform the weapon art of the Storyteller's Staff to poison him. Your objective now is to run away and avoid both Ariandel and Friede, waiting for the poison to chip down the boss' HP bar. Occasionally, Friede would become invisible and charge a miracle to heal Ariandel. Look for a golden aura, approach the aura, and backstab Friede out of the healing animation. Most likely you must perform another weapon art of the Storyteller's Staff in order to kill Ariandel.
The third phase is the most dangerous because you now face Blackflame Friede, who is more aggressive than during the first two phases. You have at least three windows to backstab Friede. The first window is when she performs the same aerial overhead attack as per phase one. The second window is when she performs a dashed, charging attack towards you. Roll into the attack, position your character behind Friede, and backstab, followed by R1 x 2 with the Raw Broadsword+10. The third window is when Friede becomes invisible and does two or three ice attacks. Roll to the side and away from the ice on the ground and follow the trail where the ice first appears to help you track Friede. She will charge up a black flame attack. Take the opportunity to position your character at the left hip of Friede (in contrast to the right hip during phase one) and backstab. Follow up with R1 x 2 of the Raw Broadsword+10.