To start, you should have: Auto Eat - Tier I, Full Mithril Armour, 40 / 40 / 40, Ice Sword, Adamant Dagger
At the end, you should have: Almost full (G) Adamant Armour, Amulet of Looting, Rune 2H Sword, 70 / 70 / 70
While your next target is Adamant Knights, you should know that levelling Attack and Defence up to 50 will effectively reduce your healing per Knight from 1700 to 1200.
Important note: DO NOT IDLE KNIGHTS. Make sure to always have more HP than the max hit of the enemy, and try to eat food right after your attack timer ends, so you don’t reset an attack in progress. Eat until full HP, or at least until you have enough HP to survive any attack. The 2.6s interval of the Adamant Knight is not really a danger provided you’re PAYING ATTENTION and have enough food.
Your Ice Sword is great for leveling all of your combat stats. You may do this at Statue, to prepare for gear upgrades, and thus your first Damage Reduction points!
Each Adamant piece has a 1/48 chance of dropping. Good luck on that! You don’t necessarily care about the Adamant Boots as there are reliable sources in Turkul Riders which also drop Rune Boots very soon from now. If you are lucky enough to snag an Obsidian Cape, rejoice as this item offers the biggest evasion upgrade of any item dropped by Adamant Knights. Its very low drop rate (1/240), however, may deter you from grinding for it. It will be a while until you replace the Cape for anything else, so you will get a lot of use out of it. There is no point wasting Silver/ Gold Bars on the Boots. Upgrade the rest of the equipment you get to (G) Adamant as soon as you get them, since each piece gives you 4% Damage Reduction. Since you will be using 2H weapons for awhile you may skip (G) Adamant Shield, but it will still be a useful shield until (G) Rune Shield or Dragonfire Shield so it is worth upgrading.
Your next goal after full adamant is a weapon upgrade. This will come from Elerine Warriors and are the Rune 2H Sword and the Elerine Spear. With 3 out of 5 (G) adamant pieces and a Silver Diamond Ring from Mummies totalling 13% DR, this monster can be safely idled with Auto Eat - Tier I, 13% DR and 540 hitpoints. Of the two drops we seek, the former is a relatively common drop (1/36) and a considerable step up from the Ice Sword (yielding double the clears/hr of Spider Forest). The Elerine Spear is a slight upgrade over the Rune 2H Sword, but it is a much lower drop rate (1/180), so it may not really be worth grinding for. It is worth noting that while both weapons are fantastic when used on their correct style(s), they are utterly abysmal at the other style(s). The Elerine Spear should only ever be used on stab to train Attack, while the Rune 2H Sword can be used to train Strength and Defence equally.
If you have 45, you can consider obtaining a set of Gloves of Silence to help with fundraising. This item alone almost doubles the gp/hr of Cows and it turns Plants surprisingly into one of the best early money makers.
At 50, save up enough slayer coins to purchase a Desert Hat. You will also transition from Basic Resupply to Standard Resupply for the rest of the game at this point. This item gives you access to Rune Gloves, Desert Wrappings, (G) Rune Boots and Sand Treaders, as well Desert Sabre that you may want to farm at one point. You will want to farm for at least Rune Gloves and (G) Rune Boots from the respective creatures in Arid Plains, as these have relatively common drop rates and won't take long. Desert Wrappings offer a nice 2% DR which will help with Spider Forest, but can be skipped as they will soon be replaced with Paladin Gloves. It is possible to kill Turkul Giants at this point to obtain Dragon Scimitar or Desert Sabre, but these upgrades are relatively minor over the Rune 2H Sword and will soon be replaced with items from Deep Sea Ship anyway.
BEWARE: Do not Auto Eat Potatoes in the Arid Plains unless you have at least Auto Eat - Tier II. You will lose all your Potatoes instantly as they will round down to 0 healing.
Killing Paladins for Paladin Gloves at this stage is somewhat viable, but they have a low drop rate and the Auto Eat threshold is quite high. Over a long period, the chance of making a mistake and dying is quite high, so it would be better to wait until you can rely on auto eat to do its thing. Around 20% DR and 660 HP.
Chaper III-B: Amulet of Looting
With a hefty chunk of upgrades under your belt, it is time to fight the first early game milestone in the Spider King. This monster drops the Amulet of Looting which is a special amulet which automatically loots gear acquired from Combat Areas and Slayer Areas. You may get it from the Spider Chest, with a 1/22 chance. This item marks the first paradigm shift in the HCCO game mode, as manual looting is now a thing of the past. Now is a good time to obtain the Amulet of Looting as before this point most monsters either wouldn't drop 100 items in a reasonable time frame, or their drops were largely not important enough to prioritise picking up consistently. Our main food source up until now has been Basic Resupply (or Standard Resupply at 50 and beyond) which do not need to be looted, so the benefit of the amulet was minimal.
As a point of comparison, by using Mithril Armour, and having around 40 / 40 / 40, it will take you around 5000 healing from food per run of the Spider Forest. With access to gilded adamant & (G) Rune Boots for DR and a trusty Rune 2H Sword or Elerine Spear, this boss can be idled with 18% DR and 590 HP for around 10 kills/hr. It is quite possible to beat the zone without having any form of Auto Eat, and just make sure you time your manual eating right, since the damage of the Spiders in the area is not too high. This may be appealing to players wishing to quickly eliminate manual looting from their routine.
Without any DR, the boss can instead be tackled with 710 HP and AE1. Check Can I Idle for any particular combination of requirements you happen to have. If you wanted to try obtain Auto Eat - Tier II before this dungeon, know that this requires 5,000,000, which would require around 25 hours of active gameplay at Master Farmer, since you still don’t have auto looting, or around 40 hours of Plant farming with Gloves of Silence. Bad idea.
Chapter III-B: Making money early-mid: Master Farmer + Auto Eat II
The Master Farmer gives a total of 14 unique items. You want to prioritize your bank slots for the most rewarding items, taking the price and drop rate into account. This mainly comprises the Tree Seeds, requiring 5 slots. By reserving five slots for the Master Farmers grind, you get a total of 84% of the GP drops. That’s around 950 per kill.
Alternatively, equipping Gloves of Silence increases the base GP/kill of every monster by 150. This makes low HP enemies such as Plants and Cows a great source of income too, albeit with lower xp/hr compared to Master Farmers.
Later on at 70 you have access to Raging Horned Elite, which drop a reasonable amount of sellable items (worth about 2,000 each kill) as well as a huge supply of Trout. You will likely kill tens of thousands of this monster while gathering food, which can easily fund the more expensive upgrades remaining, so it is not important to over-focus on earning GP at this point.
Chapter III-C: Late to mid Game food: Slayer
Now is a good time to build up 150,000 Slayer Coins as Auto Slayer is a great purchase to idly build up Slayer Coins. With them, you can purchase Standard Resupply, which nets you both a useful 150 Crab and 500 Magic Bones per purchase. This is the most efficient HP per Slayer Coin (even moreso than Generous Resupply!), and is worth saving up for. These can be used throughout the rest of the game for easy food.
As per usual, free rerolls may be used to acquire Master Farmer as your Slayer task.
As noted before, beware of Wizards and Fairies when using Auto Slayer, and ensure they can not bypass your Auto Eat threshold. They should be skipped either way, as they will consume a lot of food due to their high accuracy on melee armour.