First off, I don't claim to be a professional or anything. This is just a step-by-step guide explaining how I get most of my credits. I find that it works out pretty well.
I can get about 28,000 credits in the space of roughly 2 hours.

Step 1

-Go to (http://halo.xbox.com/en-us/Career/haloreach/Challenges) and sign in if you're not already signed in.
-Scroll down to where it says "CREATE A CHALLENGE"
-Create the following two challenges.

1
Name challenge: Whatever you want to call it to help you remember what it is. It doesn't really matter.
Challenge type: Matchmaking Firefight.
Goal: Kills.
Target: 800.
Set time limit (hours): 3 (lowest you can go).

2
Name challenge: Whatever you want to call it to help you remember what it is. It doesn't really matter.
Challenge type: Matchmaking Firefight.
Goal: Medals.
Target: 800.
Set time limit (hours): 3 (lowest you can go).

Step 2

-After creating your challenges, sign in to halo and go to the Cooperative playlist and pick Score Attack.
-You'll want to wait until you find a game of "Gruntpocalypse", preferably on Corvette or Outpost. I've found that they're easier.
-When the game starts, pick the loadout with the jetpack.
-Whenever you're setting up your crosshair and getting ready to shoot a grunt, activate your jetpack quickly.
-This will cause you to get a medal for a headshot and a medal for killing an enemy while you're jetpacking.
-Using this method, you can get almost 250 medals per game and anywhere between 110-120 kills per game.
-Here's a video showing what you should be doing if there's any confusion: http://www.bungie.net/Stats/Reach/FileDetails.aspx?fid=26504711&player=IAmLuke21393

Step 3

-After about 3 or 4 games, your medals challenge should be completed, so you'll want to create another one.
-This one should have a slightly lower goal, like 600 medals, assuming you want to finish both challenges at about the same time.
-Here's an example of what my challenges screen looks like:
-Red line indicates the first two challenges I created. Yellow line indicates the last one to finish it off.

I hope someone finds this helpful. I've been getting tons of credits from this. I've almost got enough for inclement weather.

Great guide ty.

Can't wait to spend my time doing this.

yes you have other ways to spend your valuable time
trolling dead forums(LOL)
playing runescape(LOL)

What did you just do then?

canadian/10

Kitty says: "Fuck you and fuck your opinions too."



Be nice to each other.

This post was edited by iamluke21393 on Feb 6 2012 06:41pm

sweet