The last of the three Light tank games played achievements, this is the longest and I would highly recommend trying out as many different light tanks as you can to get a good taste of variety and see if you want to work through any other tank trees.
This achievement itself is quite easy, just time-consuming. All Tier 1 tanks are light tanks, and a lot of Tier 2 tanks are Light tanks as well! Light tanks have a solid diamond by their Tier number.
Just start a game with your light tank, if you get destroyed you can just go straight to your garage and pick another ready light tank and play another match!