I'm looking for the best way.

military

Military is probably your biggest networth contributor, however some tech is also not a bad way to gain net without having to go all military and have high expense costs to go with it.

Tech = 2 NW each point (if the Wiki is still correct).

Troops = 0.5 NW each
Jets = 0.6 NW each
Turrets = 0.6 NW each
Tanks = 2 NW each
Spies = 1 NW each

For the short term: buy military
For the long term: buildings and technology (choose one good to produce, and get buildings of this type and technology of this type). Longterm you need economy to build networth.

Fastest to build net is to play commie Indy. Hehe. Then oldman jumps past you in the end and wins. Lol

Unless you farm him ~20 days before the end of the set.

now's your chance =P

I still have to do my strat change though...

Seems to me to be directly related to land. Get a lot of land early before the main land farmers are ready to go and out build them to stay ahead.

That's just an opinion, I have not done any supporting research for this theory.

From what I noticed, land only seems to be a big networth factor at the beginning of the set when countries are smaller. If you get too much of it, without having the military to defend it, then it will be taken from you. Once you are buying 100,000 jets/turrets at a time, the networth contribution of land is a much smaller piece of the pie. Although it can help you generate more money which can help buy more networth through military/tech.

Its a balancing act between spending turns gaining land, gaining money, and spending that money on things that help your country grow and at the same time help defend the land you have.

Tech is really important to gain networth fast which new players sometimes underestimate.
A casher with 10k acres and 160% bus/res tech produces the same income as a casher with 25k acres and no tech.