[Suicide Junkie]

Some comments:

And they always win big with fighting actually making them stronger rather than weaker like it has at least a good shot of doing in real life.

In real life, battles cause heavy collateral damage all over the place... fighting in the cities leaves them in ruin. Fighting in the country leaves the farmland devastated and UXO makes it dangerous to work on. The front lines typically cover both your territory and the other guys at the same time.

In space, you are fighting in open, valueless territory most of the time. Destruction and damage is limited to the warships involved. When you do fight over territory, it is the defending player's land being destroyed exclusively.

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One way to go about fixing that is to make homeworlds generate most of an empire's value, as in Proportions mod. That way the empires will remain of similar strength until the very end, and the possibility of recovering is greater.

Precisely because everything is laid out before you in black and white, Space Empires IV tends to be a very one sided game (one side tends to win big with little or no losses).

I have to disagree with that. It dosen't matter how much you know about how the world works. Its how the world actually works...
In stock, shields are so strong that ships end up being completely undamaged, or completely destroyed.
After combat, your fleet has lost a couple ships, but keeps rolling with shields recharged.

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To fix that, you need to let the little guys cause more damage before they get wiped out. Leaky shields and armor are the way to go here.
Use strong leaky armor to encourage strategies that divide up a fleet's firepower. Spreading the damage out and having leaky shields/armor means that the attacking fleet will have some destroyed ships but LOTS of wounded ships, even if they had overwhelming numbers.
The attackers now have to slow down for repairs, or leave a large fraction of their forces behind.

Either way, the defender will have a better chance. Fewer warships to fight, or more time to gather a fleet big enough to drive out the invaders.

For example, I have a list that I make in excel of all the planets I want to colonize and most importantly how many facilities each can hold *based on the breathers I have available* so I can sort it on that field.

Sort the list by "Pic" and then by "atmosphere".
Jump to the atmosphere you want, and the planets will be sorted increasing in size.

Or just sort by atmosphere and look at the pic. Its pretty easy to tell the diff between the large and small ones, and the difference between large and huge dosen't matter much; you're gonna colonize them all soon enough anyways.

I usually pick my planets to colonize based on resource value instead. I need the resources now, and I won't hit population limits for a while.

Multiple possible strategies - Gal. Civ. has different legitimate ways to win the game. In the sense that all of them will work if played at sufficient skill against the highest level of AI. SEIV really only has one viable strategy if you want to win. Get the biggest economy and build the largest ships with the latest weapons and pound the bejeebers out of your enemies. You can't use missles or fighters really (although they sometimes work because of suprise) and ramming fleets are also fatally flawed in a way that I don't want to say in case my opponent in NGC4 is reading this and removes my one chance of actually doing some damage to him

This is also where mods come in. The weapon balance from SE3 didn't quite come through cleanly to SE4.
I like to provide torpedoes with an accuracy bonus, WMGs extended range (to 11 or 12), phased (weapons and shields) reduced power, and so on.

If you're behind in sensor tech, and just can't hit the enemy, use the torpedoes. Try the WMGs on support ships that stay behind the main line of warships and carry little to no shielding. Pull out the occasional PPB ship to force the enemy to use the phased shields instead of the higher-hitpoints normal shields.

All kinds of good stuff you can do.