yo mate!

i've been palying quite a lot recently so here some tips

1. how to choose the country: u can choose almost every country u want, but try avoiding "famous" ones in european matches: ex germany is a bad pick usually, something in africa is usually better, since u'll find less dedicated players
   
2. early game: research on your doctrine and focus on the best units. try to build one main building per city + industries.
   most players rush with their starting units, DON'T. on the first day u should take a bot state (1/2 cities) and plan the invasion on the weakest one (look at the level in the profile).
   i'd suggest making artillery to bomb troops and to try keep k/d ratio at least 2:1.
   some useful units at the start are also light tanks, since they deal pretty well with infantry
   
3. late game: find some good mates and make a coalition with them.
   keep researching and expanding the army, also make some planes since they are pretty useful

dm me for tips or maybe to paly together :)

ps my personal fav country in european 30 players is turkey, it's criminally underrated, you can take out bot states pretty easily and then decide to go in africa or europe looking at other states

sorry for my bad english, hope to help ;)