Rebel Galaxy

You can start finding merchants in need of rescue from the beginning of the game in your first system. They can be found in two ways; Either when you're in warp, identified as 'Distress Beacons'- purple diamonds with exclamation marks on them. Or you can try finding them manually while not at warp speed; just fly around between stations and belts and use your pulse scanner to find local targets etc.

Near the start of the game these will be easier, you'll usually only find 2-3 hostiles (red targets), normally fighters, chasing a lone, friendly (blue target) marked as a 'Trader'. These traders are your merchants, but as the game progresses and you rescue more of them, there will be more difficult enemies to defeat.

Note: These enemies will almost always be pirates, specifically the 'Red Devil Cartel' - identified by a red ram's skull. If you are, wisely, going for the 'Skull and Crossbones' achievement very early on, it's best to avoid killing these guys and instead become neutral with them first, unlock that achievement, then concentrate on this one.

When you've found a merchant in trouble, approach them quickly (they can die) and just kill all the enemies in the area. You can press when prompted to 'hail' the trader and offer to help him out before, during or after saving him, but it is not required for the achievement.

Note: When you rescue your first merchant you can hail him and buy or sell something from him for the 'On The Go' achievement.

To track your progress; press and find the 'Stats' option, under the 'System' tab. Select it and you can see how many 'Merchants Rescued' there are. Once you have rescued at least '20' merchants / traders the achievement will unlock.