FIFA 12

Each time you defeat a nation, you are awarded 1 player from that nation. In order to get this achievement, you will need to defeat 1 nation up to 10 times, save the awarded player, and eventually use him in your starting 11. The best way to do this is as follows:

Start up Expedition and choose your Be a Pro character. When you get your random team, try to get at least 2 players from the same nation. Once you have your team set, back out of the DLC and edit the nationality of your Be a Pro character so that it matches the others. At this point, you will have at least 3 players from 1 nation and you will have to play to get the rest. First, let's make it easy. Start Expedition and adjust your game settings to the following:

Half Length: 4 minutes
Difficulty: Amateur
Injuries: Off
Offsides: Off
User Customization: All 100%, except Shot Error/Pass Error (0%) and Power Bar (adjust as desired - too high will make your shots sail)
CPU Customization: All 0%, except Shot Error/Pass Error (100%)
You can ignore the injury sliders, since injuries will be turned off.

If you are also going for the Collector achievement, you will have to play each nation 3 times. When you get to your chosen nation, save all of the players you are awarded. This will bring your total to 6. Play that nation 5 more times and you will have all 11 players needed. The players can be out of position, so if you get all goalies, play all goalies. With the above settings, you will have no problem getting victories. Once you have every player in your starting lineup from 1 nation, win 1 more game against any nation and the achievement will unlock.

Note: Not all nations are unlocked at the start, so if you just want to get this 1 achievement done, you will want to pick a nation that is unlocked early, in which case you may just want to settle for your Be a Pro character and just play an extra game or two.

This achievement requires you to win a match in expedition mode with 11 players from the same nation. To aquire these 11 players you're going to need to play the same side 11 times and each time keeping the player that you are rewarded with. You could just do this with the very first side you play against or like me, start expedition in the group of your favourite side and work you way up to playing them 11 times to create a similar squad to your national team. Just to point that your virtual pro can count towards this achievement if you change their nationality to the side you've chosen. Also you dont need to put the right players in the right positions, i had 3 keepers and no strikers in my squad and it still worked fine. To make this go as quick as possible change the time for each half to 4 mins and the difficulty to one which you can be certain of winning on. Another tactic could be to change the user and cpu game customisation in your favour, then play on amateur, score a few goals and then just go idle until the game finishes. This method takes the same amount of time but means you could be something else apart from playing the same team over and over again which gets boring very fast.
Note: You can play the same team consecutively and dont have to travel away and come back.