)Depends. My tactic ALWAYS relys on diplomatic strenght, since day 1 you must be active diplomatically. I will give a few tactics of mine:
~Playing as a smaller nation that is surrounded with weak colonies and AI: I share map with biggest neighbor and i occupy those weak states. Lets say im Turkey, i would share map with USSR, and occupy Greece, Bulgaria, French Syria, British Palestine (Egypt if included), Iraq, Saudi Arabia (this happened on 1932 map). What i use to advantage is the weirdness of the community, because most players go inactive day 7. Obviously depends on the map aswell, for the most part this is for historically accurate maps.
~Playing as a large force: It gives you a very large spectre of possibilities. Here diplomacy is the key to victory: Ex. I play as France. You can be Antifascist, and befriend Britain and attack Germany, or you can Be fascist, befriend Germany and attack UK. All in all, you should keep in a coalition in larger games with larger countries.
Economically speaking its very relative, if i am and Island nation i will basically produce a lot of navy and air force, but if i am a country with small coastline (ex Finland in 100p) i wont produce navy at all. I dont tend to produce every province barracks tactic at the beginning, my armies are mostly oil based because you have to adapt to the regions you are in. Hope i "helped", obviously i wont tell everything so you cant know if we meet once 
