This achievement is VERY easy if you have a decent light tank. My personal favorite is the Cromwell, Tier 6 British medium, however almost any tank that has a high speed stat will work.
There are several factors out of your control that affect this achievements success:
1. Your teammates.
a. They are terrible and you don't win the match.
b. They are faster than you and get the spots before you.
2. Your tank.(Light tanks, or very fast mediums) Best light tank is US premium T2.
3. The map.(In my opinion Widepark is best, followed by Prokhorovka)
So, how to do this!
1. As soon as the match starts, head full speed towards the center of the map, aiming to get the spots before anyone else on your team. If you feel suicidal and think the rest of your team can win it without you, head kamikaze style into the opposing base, dodging and turning as long as you can for best results(get an artillery if you can).
2. Best map for this is Widepark, hands down! Head straight to the middle to crest the railroad track, and if you spawned on the south side you'll probably get at least 8 spots right away if you have a fast tank(I have gotten up to 14 spots doing this). For all the other maps, aim to get to the middle of the map first between the team spawns and cruise around spotting.
3. I highly recommend continually driving back and forth at top speed for best results, especially just behind the crest of whichever hill you can hide behind.
As of time of writing this, I have a bit over 3600 matches played with 90 scout medals.
Comments and suggestions are welcome!