Polaris Species:
There are many Species in Polaris Sector, each of which has unique characteristics that make them who they are, and there is a great deal of information on each one, which can be seen by clicking on the name of each species. I have seen from personal experience that new players can easily get caught up thinking that they are all the same with different skins, but it is far from the truth and I implore you to read through each one to see which suits your play style or one that catches your interests.
Starting out:
People who are not fimiliar with 4X games, or RTS games in general might not know that these games have an economy system in place to add more depth to the game or to give more control to the players, so for newcomers, managing your resources might be a pain and/or outright confusing, so more players will decide to skip management of their resources and build a bunch of combat ships instead and this tends to lead to failure within a very short amount of time and while you do generally start out with a great deal of resources it will go by very fast if you have conflict with other races.

I recommend starting out with a Defense Station (Use Ship Designer to make your own, these are purely for defense and are stationary so make it as strong as possible. They are very effective and can take out large numbers of small fighters and medium ships) 2 Coloinzers, 2 Carriers (Default holds 10 aircraft), 2 Corvettes, and 20 fighters to load into the carriers. Once these are built I would advise to colonize very available planet around your orginal sector (Do not provoke any species if you encounter them as they can posess a larger fleet). Once you have started to colonize, make sure to set up Defense Stations (At least one) and get the economy of that colony up and running. Your economy is the life blood of your sector, the better it is, the more troops,planets, and ships you can posess, so don't overlook it.

Terrority:
The objective of the game is to expand to every corner of your galaxy, but to do this you will end up fighting other races. Make sure you are not expanding too fast or you might not be able to hold it in the long run. Setting up defenses is key to winning, you should never leave a colony undefended or it could fall into enemy hands, and if left unattended, they could cause a large amount of damage to your nearby colonies and to your fleet.

When taking terrority from enemies, you should always make sure you have more than enough ships and troops to take a sector, as you could end up losing a big portion, if not your entire fleet if you do not come prepared. Having a mix of everything is the best way to go, very few ships (Usually late game ones) can hold their own against every other ship. Diversity is key to winning

Now, between this and the tutorial you should be more than ready to begin your conquest! Look out for more in-depth guides that will come out in the near future. They will be specialized and will focus on only one part of the game. If you have any tips or tricks feel free to add me and we can work on future guides to help others improve!