and why not to join our empire?

For those not spamming...

Well, the jump between painful and masochistic, for me, has been a tremendous change! Harder than any other level-up I've done.

Best advice, know you aren't going to beat the A.I. at colonizing worlds, 3 of 'em will colonize almost, if not all of, an entire large galaxy before the first year is over.

First of all, take the time to restart as often as you like to get a map of your liking. If you get one that you REALLY like, save the first turn seperately as something like "GoodStart" so that if you get off to a bad start, you can start off again from scratch and also have knowledge of where several good planets/resources are.

Pick a number of A.I.'s you can handle. Not too many since it will be harder for you to get resources/planets, and not too few since they will become juggernauts.

I prefer starting secluded with plenty of stars around me, and hopefully the A.I.'s will be crammed together and not have so many stars around them. Try and colonize planets in groups too instead of being really picky and getting all of the good ones, yet leaving them scattered, it leaves you too open for influence.

They will usually start to declare war after the second year is done, sometimes sooner though. The best indicator of when they are preparing to declare war is when you stop seeing colony ships flying around. I find that cranking up research and then going for the first tier of econ./prouction/research is a good start. Although, usually go Xeno Research -> Planetary Improvements -> Xeno Economics -> Impulse Drive -> Trade -> Advanced Hulls -> Interstellar Republic (Not always, but I at least get "Alliances"), then finish off with Soil Enhancement before turning off Research for the rest of the first year. I only told the techs I reached because I would assume you'd know to get the prereq.(s).

Try and grab as many planets as you can, I usually avoid the class 8 and below in hope of finding better planets. I sometimes restart after the second year depending upon how many colonies I grabbed or if one A.I. starts to really dominate early on and picks me for its "bitch".

I have a few Super Projects I consider a must have, even if they are trade goods, I will trade almost anything for them to get them. Restaraunt of Eternity is VERY valuable since it will help prevent influence take overs. Diplomatic Translators are also a must have. Xinthanium Hull plating is valuable not so much for you, but keeping it from them. It also makes a great trading item if you need to get relations up. Any morale enhancing trade goods are great too since it adds to your natural and thus let's you crank up taxes.

Don't do what the A.I. does and put a StarPort on every planet since some planets just don't produce as good as other. The "Starship bonus" is a lot more valuable then it seems. It only affects the planet it's on, but what it does is give you it's percent as an attack bonus for ships built on it.

All in all, good luck, you'll enjoy it because it is hard, and don't feel bad for restarting even later in the game. Diplomacy is VERY important since it will help you get techs later on you don't want to take time getting.

Oh yeah! Pop. approval penalties cap at -80%, which occurs at 25.0b people, and at the same time, buildings won't lose anymore effectiveness for any populations over 25.0b. So if you have a 95% approval with 25b, you can throw on plenty of farms and never drop below that unless you destroy morale enhancing buildings or raise taxes. At that point, a VR center adds +10% morale, and a Stock Market is about +3%.

oh yeah, winning on maso...

it's supposed to be hard. if you're trying to get metaverse medals like the good folks above me, the advise is very good.

on war, ships, combat, and upgrading
early in the game, war isn't a huge threat. unless you're really out of your legue, your biggest concern with early wars should be preserving your mining bases. i feel it's too difficult for the AI to build up a real invasion force to make it much of a threat, and militaries are all so relatively weak that a strong industry and research base will allow you to catch up to any early military threat fairly easily.
in earlier wars, i'll usually have the tech to build a fairly formitable medium ship. i throw defenses on it as needed and available at this point. i rarely use multiple on defenses (only if i'm fighting two enemies on the same front). rather, if my armored fleet suddenly goes to war with a missle-bearing enemy, i prefer to upgrade the ships from armor to PD. they keep their level and HP bonus, and upgrading to different defenses of the same level is not overly expensive, IMO, especially if you have a strong economy.
i don't ever bother putting defenses on small and tiny ships. it just isn't worth it to me. they make better cannon fodder, since the game is programmed only to target the weakest ships first.
later in the game when weapons and production are getting stronger, i start using medium ships differently. i'll have at least two basic models. the one i continue producing is always cheaper; more lightly defended and (if i'm playing evil) regular weapons instead of psyonic ones. when they're right out of production later in the tech race, medium ships are more vulnerable. so what i do is hit a balance; if they reach level 3 or 4, i upgrade them to the expensive model. if they get blown up before that, i haven't lost as huge an investment.
another change i make later in the game relates to something ZeroGman said. early in the game, i put starports on few planets. later in the game, especially if i'm fighting extended wars, i actually go around and slap a starport on just about every planet. why? fighters are cheap. i have build so many variations on fighters because they can be produced quickly, even on planets with no industrial structures. most of my fleet typically has 2 engines. regular fighters escorting these fleets are also outfitted with 2 engines and the most weapons i can squeeze on (i usually prefer missiles and railguns). however after i go to war, if my fleets are on the offensive in enemy territory i build figthters with 3 engines and usually only 1 weapon comp. they can rush in much more quickly to reinforce the fleets. this usually keeps my capital ships unharmed, but also constantly gaining small amounts of XP. engines (especially warp5 and up) are cheap, especially compared to weapons.
if you've got money to burn, you can even produce super-cheap blanks on your planets and upgrade them each turn. but that's more wasteful than i can usually justify, if i'm trying to win at least.

also, you can try starting out playing a mod and give your face some nice bonuses; consider them training wheels.