What is the best strategy for a beginner?
and some tips on how to make my economy grow faster?
If you wanna get your eco growing faster, forget all Leila said.
Economy means population, so your most important target is a 2nd province (plains prefered). This will need a bit time, because centralisation has high building costs at start and you need also 500 archers/spearman, but after you got it, you ll start with some resources in your new province, so centralisation isnt that expensive at all.
Dont build up granarries at lvl 6 at start, its too expensive and not worth. You would get only 1,2 more people per hour, but a new province will give you 36 per hour, if its a plain province. This means, if you get a 2nd province 1 hour earlier it has same effect than 30 hours of owning 1 lvl granarry.
At start, you should build a fortress lvl 1 first. Than granarry lvl 4, than build all you need to get a new province. Colonizing with Archers is cheaper than with spearmen and spearman are a bit sensless at start - also for attacking, but you ll need them later --> build them later.
After you got your 2nd province, go for granrries lvl 5 in both provinces and if you can afford it with no problem, go for lvl 6.
Medicine is only expensive, but not powerfull at start. It will raise your populationgrow 5%, but your grow is so low, that its better to wait a bit. I never research it until i got uni lvl 4.
University and Architecture are very important in this game, so you should try to raise them often. Best is, if you build in waves. You start raising uni, make some researches and then you raise architecture at same lvl. Then you build.