You should really try designing you own ships instead of using the lame core ships. I NEVER use core ships except at the very beginning for the initial colony, etc ships.

The Gal Civ Wiki is also a good reference that is fairly up to date regarding the current version of the game.

Sections of it also give some insight into gameplay strategies.

[link="https://www.galciv.wikia.com/wiki/Galactic_Civilizations_Wiki"]https://www.galciv.wikia.com/wiki/Galactic_Civilizations_Wiki">Link

I should start out by saying that I am only playing for a military win.

Yes, scout ships are lame. Build colony ships to explore and colonize.
I focus on building the economy and making faster and more powerful ships.

My pre-built colony ship (in my opinion) has too few colonists. I reland it on earth and fill it to 500 and then send it out. This helps jump start your first colony.

I buy the first factory on earth and buy the second a few teams later.
I set the taxation low to get 100% approval to increase the population (more pop means more revenue). You don't lose too much at first but after a while when your money gets to 1000-2000 you have to go to higher taxes (and a lower approval rating) or you will go bust. Don't let the approval rating get too low or you will get little pop increase and planets could revolt. I try not to let it go below 60%. Ideally, you get better pop increases when it is 75% and even more at 100%. But that (after the initial few turns) may come later.

On most planets I start out building 2-4 factories first, then entertainment to get approval to go higher, then build research and trade centers.

There are several techs that can help your econony and production. Look at your choices. I try to move to the republic and that helps the economy some.

I tend to try to outcolonize the ai's (but I usually only play against 2 or 3 ai's at a time). I research to good and evil eventually and I like neutral because it immediately increases the number of usable squares on the planets. All habitable planets go up by at least 3 squares. Some more.

I don't build many military ships until I have done much of my colonizing. This may not work on the harder levels. I don't go after the other ai's until
I have overwhelming power. Then I research to get plasma weapons and medium ships. I put two plasma weapons on medium ships and send them to enemy planets to knock down any ships they have. Then research troop ships and send them in to invade.

I am sure some can improve on these comments. I am playing at just above normal and frankly it's hard to lose.

At the beginning you may want to make sure that your opponents are not boxing you in. You can set the mini-map to show where you and your opponents are. (I think it is the first icon in the second line.) If you don't like your position, hit Ctrl-N and it will build a new map without having to go through all of the earlier steps. Keep doing this until you like your starting position. It's nice if you have several stars with you in the same square. Or in a sqare next to yours. You may get some quick colonies that way.

I tend to colonize planets with 10 pq's (squares) or more. Sometimes I may take a 7, 8 or 9 near the enemy ai's since it makes it easier to get ships to the enemy (the range of you ships depends on the support modules and how close you are to a friendly planet).

After you have a few planets building colonizing ships, build a few survey ships (you need a couple of techs--one is sensor). Look for anomalies that bring in money. It usually comes in 500, 1000, or 2500. These can really help you get through the lean times at the beginning when you don't have much money. You can use that money to quick build things on your planets. If I have the money, I mainly will quick build factories and a few other things. Usually though I wait to quick build until they are 2 turns from completion. Or it gets too expensive. I rarely quick build ships as they are rather expensive.

Make sure the focus on your initial planet is set to social so that things get built more quickly. Later you can switch the focus to military when you are cranking out colonizers and other military ships.

I am hardly a big expert but I am having fun.

also, it helps to obsolete older ship designs sometimes which reduces the clutter.