General Strategy:

Your top priority in the early game should be generating technology points (circles) since they can be reinvested in technology cards and hence work like compound interest.

Towards the end of the game, the cube resources are getting more important when surplus circles become completely worthless.

The most critical decision is what technology to develop next. Try to match the thresholds 4, 7 and 10.

It is rewarding to know the technology cards very well since they are the same every game and always available. Moreover, they have some systematic oddities: most notably, the level 2 technologies each produce 2 circles required by the column on its right but only one 1 for the left one. Hence, researching technologies from left to right is easier than vice versa.

The Different Cube Resources:

Sages: Consistent but mediocre point generators. During the Challenge events, they can help to gain small edges in circles if you don't have to disrupt your overall plan for that.

Ambassadors: Because some leaders generate resources over time, you should get one of them as soon as possible. In particular one of the five leaders who cost only 2 and generate one circle are extremely efficient because they generate those in the same round in which you buy them and because of the compound interest effect. Hence, opening with Tyranny is strongly recommended in general.

Soldiers: The effectiveness of soldiers depend strongly upon the specific Battle event since some of them have very large margins between the rewards for the different ranks while others have rather small margins.

Builders: Building small non-military wonders are very cost-effective since each of them contributes to a challenge. Investing in military wonders is the more flexible way to gain soldiers than via technology cards.

Philosophers: Mostly translate to just points. The resource bonuses at the beginning are not impactful compared to other investments, so this should rather be started from the midgame.