Remember the type of improvements matter improvements are buildings on planets. W.hen you line up the same type of building you get bonuses.
You should have some resources in space constructors is how you get them. mainly promethium, anti matter and duranthium to start off is most important. build as many colony ships as there are free planets in range. Exploration early is essential. Good thing you start out with a survey ship. You will notice dots in unexplored areas they are stars, and some of the planets are habital. When a dot turns into a star then you can left click on the star. Now in the lower left corner of the screen it will tell you wether you have habital planets, resources, and asteroids. You can mine only asteroids in your influence, and mining asteroids wont help if they are to far away.
To my opinion asteroids mines is the most important to spend your money on. To mine an asteroid click on it, and then look in the lower left corner there will be a box to build asteroid press it you will lose 100 credits for a gain of1 point of production on the nearest planet. Everything is calculated on the planet starting with production.
To use a resource on a planet you need to improve it. Resources help you build things different space, and planet resources build different things.
I recommend building a shipyard right off the bat. Then factory stuff next.