Copy pasta the following into adom.cfg:

If you want to know the finer details, read on.

Some things are certain in ADOM. Among these are the fact that you will die and that you will need gold and other cool items to progress. For help with the former, I suggest finding another guide. If you are interested in making it easier to sift through the useless junk then I suggest that you read on. I am aware that you can easily pick things up using the mapped keys, but this guide will help you tell the game to automatically pick up important items like gold and rings. This should leave the loot list less cluttered (especially after multikills) so that you can easily spot that 36s spear with minimal cycling.

First thing you need to do is find your adom.cfg file.

Windows:
It is normally located in your adom_steam folder. This is usually nested under an ADOM folder in your Documents.

Other Operating Systems:
adom_steam should be in your home directory, otherwise do a search for the adom.cfg

If you open up this file with a text editor you can see that there are certain variables that you can configure. These are all commented out (they will not be read by the program) with a hash #. The one that interests us is on line 52 - Auto_Pickup.

Copy Auto_Pickup (don't forget the underscore) to a new line. I put it in alphabetically after the comments, but anywhere should be fine as long as it is not directly after a #. Thereafter type an = (equal sign) and the symbols of the items you want with a , (comma) between symbols. If you are familiar with the ASCII (non-tiled) version of ADOM, the items' symbols are exactly as they appear in the game (bar rocks and food for practical reasons). For the rest, see the handy table below.

The final result may look something like this:

Feel free to disagree with my recommendations. These are what work for me and it would better serve new players who are not as familiar with the game.

An [ (open square bracket) is used for armour, shields, cloaks, boots, girdles, gauntlets, and helmets. Steam has issues with the parsing so I put it here below.

An example list to auto pickup what I consider any character class should always pickup, would look as follows:
This tells ADOM to auto pickup gems, amulets, rings, wands, potions, scrolls, and gold.

• The Auto_Pickup variable has an _ underscore.
  
• Symbols in your list should start after an = equals sign and be separated by , commas for the program to read it correctly.
  
• The second equals sign is not a mistake; it is to add rings to the auto pickup list.
  
• If you put a # hash before your line it becomes comment, isn't parsed by ADOM, and won't make any difference to your game.
  
• The Auto_Pickup variable is a string of characters (or just one) separated by , (commas) after the = (equals sign).

It is important to know that setting up the auto pickup feature as above still does not take away the time needed to pick up the items. The items in your config will just be automatically picked up and added to the inventory. This means that you should be mindful of stepping on items when there are enemies around or when the environment is otherwise dangerous (e.g. being underwater or engulfed in flames). Luckily there is a key combination specifically mapped to ensure your safety.

By pressing Ctrl and a (simultaneously) on your keyboard, you can toggle the auto pickup feature on and off.

This is may be useful when:

• in a hostile situation where taking the time to bend over and putting something in your backpack is ill-advised
  
• touching items may be ill-advised (you'll know quickly if this is the case)
  
• you don't want to pick up (almost) everything in the goods store

May thy wisdom be omnipresent!