Either rockshell armour, spined armour or skeletal armour. You only need the helm, body, and legs. Spined armour is currently cheapest on the Grand Exchange but be very careful when purchasing as it does not buy immediately.
Items needed: 500 Coins, 3 Molten glass, 3 Buckets of sand, 3 Soda ashes, slightly drained Summoning points, Bucket of Milk or Bucket, Pet rock, Rockshell armour, Spined armour or Skeletal armour
After that, head to the Council workman on the bridge between Seers' Village and Rellekka to claim your Easy rewards for completing all easy tasks. Run back to Rellekka (or use your newly Recharged Lyre) to claim Medium rewards for completing the Medium Difficulty Tasks by speaking to Yrsa.
Lunar Island, Miscellania and Waterbirth Island[]
Items needed: Weapon and armour to kill 3 Dagannoths, Food, Coins, an Uncooked pie, 1 astral rune, 5 fire runes and 4 water runes