I've been playing MOO2 for years and I always use a custom race. My current race has Tax:1, Rich Home World, Creative, Warlord, and Dictatorship. I don't like using Lithovore or Tolerant (the former means you don't need to produce food or freighters to transport it for you race, while the later means you are immune to radiation and toxic environments). They take a LOT of the challenge out of the game because they remove some of the more common hurdles you need to overcome.
Creative is important because when you complete research, you learn EVERYTHING in the box. Like Class V shields AND Gauss Cannons or ALL the pods (Battle, Troop and Survival). No need to pick and choose which advancement you want, you get them all.
Warlord is a favorite of mine because I've found that the more experienced ships actually give closer to maximum damage per shot than inexperienced ones. Needless to say, I also advocate refitting existing ships as your tech advances for this reason as well. I refit when I advance shields, armor AND weapons tech- but rarely just because of only one unless it is a big jump in tech like going from Zortium to Xentornium armor or I gained Damper or Reflection fields.
I always use Tactical combat because I prefer to design my ships myself rather than letting the computer do it. The computer will waste space on useless things like Scout Labs long after they are needed. Unless I have Subspace Transporters, Reflction fields and Damper fields, most ships only get Battle Pods. Anything bigger than a Battleship gets an Automated Repair Unit when I develop it.
My ship designs are very simple. I focus on doing the maximum amount of damage per turn. Period. If you want to win, you have to kill me faster than I can kill you. If you can, I want to carry as many with me as possible to make it a Pyrric victory on your part. Battle pods with a max number of Heavy Mount guns (until I get Subspace Transporters, I like Mass Drivers, Disrupters and Gauss Cannons because they don't have a loss of damage due to range- after I get it, I swap to Mauler devices and Plasma cannons), 1 (cruisers) to 5 (Doom Stars) missiles or torpedoes and any left over space is used for PD weps (mass drivers or phasors if they are a 1 or 2) or bombs (nukes unless antimatter are a space 1 item) are my standard load out.
Tactics wise, I have 2 very different styles. Early on, I want to hit HARD at long range with a minimal loss of damage. You can get in 2 volleys with Mass Drivers doing max damage before someone using the 'superior' Gravitons get into their best range. Defensively, this gives your Ground Batteries, Star Bases and Battle Stations an advantage as well because the attacking ships haven't close to THEIR best range before you can do serious damage. I will take on a numerically superior force armed with Neutron Blasters with Zortium armor, Class III shields, Pulson Missiles and Mass Drivers all day long if I've advanced far enough to be researching for Gauss Cannons at that moment (at that point you have reached the maximum limit of size reduction for the Mass Driver before advancing to the similar- but more effective- Gauss Cannon, so you can pack more of them into a hull. I looked at the damage ratio and switching to the space 20 Heavy Gauss Gannon wins.)
The other style I use is predicated on having the Subspace Transporter and is basically a mugging. I want to attack, jump right in their face and blow away as many ships as I can in the first volley. That's why the Plasma Cannons, Plasma Webs and Mauler devices come into play. If I'm out numbered, I build a LOT of Cruisers with Stasis Fields. Once I've blown holes in the opposing formation with the Battleship and bigger classes, they jump in and freeze the bigger surviving ships. I use it as a force multiplier. By the second or thrid round, it's basically over. They can have 100 Doom Stars but if only 1 can fire at a time, it ain't doing them a whole lot of good if they don't take me out quick enough.
If faced with a technologically advanced enemy, I build a specialist ship. It's a Titan armed with 6 tractor beams (the number needed to imobilize a Doom Star), Death Rays if available and Neutron Blasters. It has Troop Pods and transporters as well as Battle Pods and a Subspace transporter. That way, I can take THEIR ships and use them against them or scrap them for tech advances. This one works well against the Antarians as well.
The only other specialty ships I build are a Titan with a Stellar Converter and the rest of the space taken up with Disrupters because I leave the Subspace Transporter out or -if I've advanced to Physics IV or higher- a Battleship set up the same way.
I don't like building big ships like Titans and Doom Stars in general. They are necessary in the late game but I rarely bother with them until I've taken Orion. Basically, they take too long to build early on. I like having a bunch of smaller ships earlier in the game. My first ships (other than a couple Scouts) are always Destroyers (Class I shield and 4 Heavy Mass Drivers initially and up to 6 Heavy Mass Drivers or 5 and a missile eventually). After building about a dozen of them, I build Cruisers (max Mass Drivers plus 1 missile). Once I have 6 or 8 of them built, I move on to Battleships (max Mass Drivers plus 2 missiles).