With allied states:
The Terran Empire is a reclusive nation, but it treats its handfull of allies with the utmost respect, and won't hesitate to render aid whenever it is asked for. It also charges lower prices for it's export materials and will pay more for imports than with regular trade partners.
With trade partners:
The Empire maintains close ties with it's trade partners, but keeps them away from interfering with regulations and politics. If a trade partner gets too pushy, an embargo will be implemented until the other nation withdraws from it's position, but trading will continue normally once such a situation has been resolved.
With neutral states:
The Empire doesn't trade with nations who haven't spoken out in the Empire's favor, but the government tries its best to be both friendly and treathening to prevent any sudden hostile activities.
With hostile states:
The Empire keeps a close eye on nations who are outspokenly against the Empire, and will have military units posted near their borders in case war breaks out. The Empire does maintain contact with the hostile land's leadership to try and diffuse the situation peacefully, but the Empire won't hesitate to attack once provoked.
With enemy states:
A state of low-level fighting is perpetual between the Empire and it's enemies; with by military action, cyberwarfare, propaganda and terror tactics.
When in war:
The Empire will launch continuous attacks and invasions into the enemy land, and will request assistance from its allies as soon as war erupts. Once the Terran war machine is fired up, it will never stop fighting until some sort of victory is achieved.
The Empire will only once offer surrender to enemies who are near defeat; if they refuse the Terran Military will destroy the entire enemy land.
Aftermath of a diplomatic failure: the Galactic Assembly capital city after being hit by an ion cannon.
If an enemy wants to make peace before the Imperials offer surrender, the Empire is willing to listen, as long as the enemy nation is willing to pay tribute to the Empire. If this demand is refused, the war will continue.
When on the losing side, the Empire's people will fight to the death. If a ceasefire is offered, the Empire will only accept if there are no terms it has to hold to save for the withdrawal from enemy terrain and the discontinuation of military action. The Empire will never accept surrender. No exceptions.