What loadout does the guide recommend?

Play Support, buy the Double-barrel Boomstick first, then an AA12 a few waves later, replacing the basic shotgun.

Which part of the guide was patched out?

The gun-sell trick: dropping and picking a gun up again added 50 dosh to its sell value, and from the 1009 beta update you cannot add extra value to dropped weapons.

How do I ask teammates for money?

Use text chat (Y by default), voice chat or hold Z for the built-in voice menu and move the mouse left to ask for dosh.

Perks & Classes

KF2 Mr. Foster Support Guide: Boomstick, AA12 and Dosh Tricks

Under a joke tone, this guide teaches a real beginner plan for Killing Floor 2: play the Support perk, buy the right shotguns in the right order and aim for the head. It is written around Mr. Foster, one of the playable characters, and was last built around the Early Access beta. Treat the numbers as dated.

Step 1: join properly

Do not start on Normal unless you truly have zero experience; pick a harder difficulty.
Play as Mr. Foster (a character choice, purely cosmetic).
Use the Support perk rather than a low-level, weak perk such as an unranked Commando.
Press Ready.

Mr. Foster character selection Pick Mr. Foster as the joke guide demands.

Support perk selected Support is the recommended perk.

There is one exception to the perk advice, described in the bonus step below.

Step 2: earn dosh

Dosh is the in-game currency. Kill Zeds with the left mouse button to earn it, then visit the Trader.

Solo. If you joined an empty server, you earn dosh only by killing. Buy the Double-barrel Boomstick first, and a few waves later add an AA12, replacing the basic shotgun. Selling random weapon drops speeds this up.

The AA12 at the trader The AA12 is the goal purchase.

Co-op. Check the wave number when you spawn in. On wave 1, play as in the solo section until it finishes. Between waves, go to the Trader and find your teammates (shoot at something suspicious a few times; a real teammate does not get hurt). Then ask politely for spare dosh:

Press Y for text chat (default).
Press Caps Lock for microphone voice chat (default).
Hold Z for the built-in voice menu and move the mouse left to ask for dosh.

Keys may differ if you changed your bindings. When you have enough, buy the Boomstick and the AA12.

Step 3: win the game

Use the AA12 for its penetration and firepower. For large Zeds, the guide's "secret technique" is simple: aim for the head. The Boomstick can also hit the head; use both barrels for massive damage. Practise with the AA12 to control its recoil.

Aiming the AA12 at a head Headshots are the secret technique.

Bonus: the old "Foster meta" (patched out)

Start the game with a high-level Medic or Commando perk, then switch to Support and play it for the rest of the map. This combined Support bonuses with Medic or Commando health and armor, at the cost of opening the perk menu each time.
A bug added 50 dosh to every gun you sold: drop the gun and pick it up again before selling. It added the bonus once per gun.
The build 1009 beta update removed this: you cannot add extra value to dropped weapons, and perk bonuses are disabled instantly on a switch.

For serious Support advice see KF2 Support perk guide and the character overview Mrs. Foster review.

FAQ

What loadout does the guide recommend?: Play Support, buy the Double-barrel Boomstick first, then an AA12 a few waves later, replacing the basic shotgun.
Which part of the guide was patched out?: The gun-sell trick: dropping and picking a gun up again added 50 dosh to its sell value, and from the 1009 beta update you cannot add extra value to dropped weapons.
How do I ask teammates for money?: Use text chat (Y by default), voice chat or hold Z for the built-in voice menu and move the mouse left to ask for dosh.