Best way to relieve tensions between races?

Build up your military. When your stick is bigger than theirs, they won't be so mouthy.

Make trade routes, Send some econ and research treaties to races you want to be allies until your done with them. Ah ya about influence star bases they dont make you friends with the neighbors it could lead to war or if your stick is bigger than most then you might be fine. If you want to survive then you might want to kill off the weak and take them over... though everyone might get they idea of what your trying to do but you will get bigger and bigger so they will just start preying you dont crush them. Gifts sometimes work so your relations can be good for longer, but this doesnt always work... that said good luck.

Military, trade routes and to a lesser extent treaties. Try to get research treaties as early as possible, then establish trade routes to those neighbours you don't plan on conquering.

I think my problem is lack of military. Usually, I avoid having any military units until someone declares war on me.

That seems to be pretty common. It was definitely an issue for me early on. The easiest solution seems to be slapping a couple weapons on a cargo hull (preferably stinger missiles early in the game) and let them hang out on your planets. You get a pretty good early-game military bonus and they are relatively cheap to build.

I always arm my survey ships. Just one or two points of weaponry, the survey module and lots of engine and life support. If hostilities break out even a cargo hull surveyor with one hp can take out a ton of unescorted transports, unarmed starbases and of course the enemy's flagship.

Also, if the surveyor hits a starship graveyard to get some extra hp (or you have a tech to add hp modules), an armed cargo based survey ship can be upgraded to a serious warship with tons more space than anything the enemy will have early in the game. I'll keep upgrading them throughout the game and by the end they're loaded with Aeron Missile defence, Doom Rays, tons of hp . . . and of course, still the survey module. If anyone wants my anomalies they'd better come loaded for bear

The first thing you want to do is build a rudimentary fighter with the tiny platform. If you have no military, the other races will perceive you as a weakling and start bullying you. Make sure to be friendly only to those who are similar in your ethical alignment. There is nothing worse than having your main trading partner declare war on you because you are not good enough or bad enough or neutral enough. When i do create research and trading partners, i always make sure that the race is weaker than me. That way that particular race will be subservient and grateful that you will trade with them.

Does anybody know exactly how the computer is calculating perceived military strength? Is it better to put a small weapon on a bunch of ships, or put more powerful weapons on fewer ships?

"total offense + total defense + 0.1 * total HP" was what another had said in a post recently.

I dont know what that means. How does that tell me the most efficient way to boost my perceived military strength?

Build a military. Always. Always, always, always. Keep a look at that military chart and always try to be in the top third.

It appears to mean that it doesn't matter to the formula above if you have a big ship with a lot of weapons or several small ships each with one weapon. What matters is the total. 10 ships with one offense and one defense each calculates the same as one ship with 10 offense and 10 defense. It is up to you to decide which is more practical and useful for you to produce.

Edit: Oops.... I didn't take into account the total HP. In that case it would probably be better to go with the "many ships" senario, at least in the early game since the only large ship is going to be a cargo hull with only one HP.

A small hull with a pair of Stingers represents a lot of firepower in the early game. A few of these will give you the dominant military. I put them in orbit around my most important planets to prevent a sneak attack. Later in the game you have the option of upgrading them using your latest technology. That can be expensive but it's a fast way to move your military back into the lead if you have neglected it for a while.

It seems much cheaper to upgrade the defenses. They are generally smaller, so you can fit more on any given ship.

Simple answer is if they are more powerful and likely to crush you soon.

Send them gifts, money + Techs, these help *short term*.

Gift them a treaty, this will give a + on the diplomacy screen (expensive, as you could get more for this elsewhere, but less expensive than war)

Trade with as many of their planets as possible, gives a ++ on the diplomacy screen.

All this is to just keep them of your back as long as possible, in the end it still won't matter, you need a military rating. So: As soon as you have a weapon tech, and get one early, start building cargo hulls stuff them full of weapons. Its the cheapest way of boosting your military early on.

Did I skip over anyone's suggestion to improve your diplomacy? If so, do that. If not, then do that anyway. Research the trees that give diplomacy bonuses. Races like you better when you can smooth-talk them. Trading, treaties, and at least a visible military also help.

I've found that if I rush Interstellar Republic, nearly every race, even if I do nothing to them, will be 'warm' to me for a very long time. The Drath don't even pay people to try to kill me.

There are some trade goods and/or galactic achievements that provide substantial bonuses for diplomacy. Certain political parties also increase your diplomatic skills. The government tech research tree enhances diplomacy and influence bonuses (and economics).

Combine all or most of the above and you should be able to gain a ++ rating for diplomacy with most of your AI competitors. Strong diplomatic skills and trade/research treaties will keep most AI races friendly with you into the mid-game even when your military is weak.

If all the races hate you, it might be because when you start the game you play as a 'good' race, and pick all of the 'evil' races as opponents. This will make them almost automaticaly hate you. Like all of the other people sayed, build up your milatary, build more trade routes, and most of all, stop peein' off the enemy!  

A. A good beer down the pub!

If you are playing TA you could have a cargo hull with a few hardpoint on it and then put some weapons on it. It works for me.

To all those folks who said military is key to maintaining peace..i say rhubarb! lol there is no doubt a strong military helps maintain peace especially with those you are ethically opposed too it is not by any means "necessary".

Almost every game i have it is usually 1-200 turns in before i even build ANY ship that isnt a constructor, miner, surveyor or colony ship.. and i do this the vast majority of the time without Any hostility from the other species. My usual technique is to build a bunch of economic starbases too along with Trade research help fost trade routes, then make at least one trade route with every major and minor species you can reach. I also tend to research diplomacy and influence enhancing tech early on too as this makes any dealings with the neighbours go more smoothly. i also find it helps to tech trade or throw a handful of credits at the neighbours too (tech-wise it doesnt have to be anything cutting edge and never anything that can be used against me), I like trading the soil enhancement, habitat imprvement and terraforming techs most of all as they seem to be valued quite a bit and go a long way into ensuring the neighbours colonies are max tile available by the time i decide to pop by and invade them or cause them to rebel to my side by building influence stations that catch them in thier radius.

Another handy trick if a neighbour does declare war on you is to via diplomacy throw some cash or a few techs at a couple more of your neighbours to declare war on the race who declared war on you, this tends to distract them somewhat from throwing everything at you and gives you a dozen or so turns usually before they all declare peace with each other again at which point you too should be able to either negotiate a peace with them again yourself or mount a counterstrike.

Form an alliance ASAP. If war is declared, your friends should take some hit until you get a decent military going.

Make a strong military, because if you check the relations report you will see that that they dislike you more because of a weak miliatry

One I quite like is get them to go to war with each other (via trade screen, money or tech as you prefer - I prefer money usually).

I always aim to make sure that every civilization is in at least one war at all times.

Combined with having a top quartile military that tends to mean you can avoid wars until you want them.

Franbo