Ok, therefore you adapt your strategy with the enviroment, but is it possible to be totally unaware of the enemy and at your first contact to be destroyed?
If so, do you plan a general strategy? (like a fleet docked in the home planet with a specify armament)
Well... Let's look.
First, you may have different game settings. I, for one, started with 0% NPR generation chance, meaning my ships entering a system won't spawn a new Non-Player Race. Then, I had 2 "starting NPRs" that I could stumble into. Plus default SPOILERS races settings. That alone could change a lot. I grew complacent fast and did not build up a big navy for a while because of the game settings.
Then, policies. How do you plan on expanding? Colonizing/terraforming? Harvest fuel or refine on planetary bodies? Do you want to, or do you HAVE to because there's no other option? Do you want to bravely explore all surrounding systems, or do you want to do it covertly? Are you afraid about the prospects of alien empire seeing your ships? Do you plan on shooting at them at first sight or would you rather have peace?
Then, comes the ship types/weapons & their employment strategy/tactics preferences. Do you want to focus more on guns or missiles? Both? Mixing it up? How do you want your fleet composition to look? How much resources do you have on hand that you can spend on building these ships? How much resources income do you have you can spend on MAINTAINing these ships? How expendable are they? How cheap they are, and their equipment?
All these points correspond to certain technologies you need to get and then maybe keep improving. Heck, when I got mineral shortages, and was unable to build ANY new ships at all, I switched most of my research to improve mineral production tech. On the other hand, terraforming and fuel harvesting played almost 0 role for me. Also, I overengineered my ships to the point I could not afford to have a large navy. But I went for a peaceful solution in relations with my neighboring NPRs, even after a small shooting war.
So there's lots to think about, given specific circumstances.