Brink

This should be one of the first achievements you get.

It asks that first bring up your Objective Wheel (the radial menu from which you select your current missions and objectives) and select an objective, then consequently complete it.

The objective wheel is brought up by holding down UP on the directional pad. Select your mission with the right stick, and release the Directional Pad before you release the stick.

This is easily achievable on the RESISTANCE mission 'Day 1: Getting Answers' and should also come bundled with the achievement 'Oh I'm sorry, was that yours?' if this guide is followed.

From your menu, select 'Campaign' - then 'RESISTANCE - Day 1: Getting Answers'

Settings:
Visibility: Solo
Play Mode: Solo
Difficulty: Normal (Probably irrelavant, but I didn't want the bots to be so stupid they'd fail to find the fight, and end up lingering near the objective.)

When the match begins, wait ten seconds or so for the fighters to engage in the central area. Then bring up your Objective wheel, and select the objective "Capture Enemy Supply Command Post" - if the enemy haven't managed to capture the Supply Command Post yet, that's okay, they will have by the time you get there. Selecting this objective will highlight the Command Post through walls - Left 4 Dead style.

Your mission is to take the high road, and make your way to the objective with as little enemy contact as possible. Once there, drop down next to it, clear the area of any enemies, and before you begin capturing, quickly bring up your Objective Wheel and reselect the same mission before beginning to capture it by holding X.

A friend of mine had a little trouble with this achievement, and called it glitched. In an effort to prove him wrong, I did the above method about five times in a row - always the two achievements blipped for 20 points.

Good Luck!

This is a relatively simple achievement. Just pull up your Objective Wheel mid-game by holding Up on the D-Pad, select a simple task (like capturing a control post or repairing something) and complete it. The achievement should show, if not just keep at it. Mine didn't appear until the third objective I completed using it.