Upgrading

[FazCraig]

Why does upgrading the very basic resuorce structures so expensive?

such as wood and stone/marble

Progress is so slow without these.

[Seanery]

At early game you shouldn't upgrade so many buildings, but building as many buildings as you can will help you with the resources.

[Menla]

Hint: It also very smart to check out the 'Resource-map (https://picasaweb.google.com/lh/photo/hiye1oQ8qfGH6D8CAe98Ag?feat=directlink)' of the island. On locations with two resources place one building, and upgrade it at least to level 2.