There are ways to go, mostly depending on the technology level and ways of progress to it that your civilization would have taken:

No matter in which age you are a FTL civilization would be heavily dependent on computers and cybernetic warfare, artificial intelligence and network protection would be a significant part of every major conflict.

The earlier you are the less advanced your weapons will get and on the low tech levels will be faced with two major choices - use massive barrages of missiles and hope some hit or go in close with railguns, cannons and other weapons. Naturally space crafts would be also used to provide a long-reach alternative to missiles. Fusion or fission reactors would provide power for ships.

As time progresses you would probably develop lasers enough powerful to damage ships, shielding systems and plasma cannons. The much quicker lasers would slowly replace railguns as anti-craft turrets. Antimatter warheads might start to appear in larger missiles (history has shown that it is easier to use potent energy reactions as weapons then as a power source). Power would probably come from advanced fusion reactors.

With the invention of a practical anti-matter reactor you would see that near-light speed plasma weapons are used for long-range attacks, together with powerful lasers, railguns returning as medium to near combat weapons and firing at high speeds, advanced strike craft run on miniaturized fusion reactors equipped with shields and missiles equipped with pin-point accuracy used together with lasers to provide anti-craft firepower.

Nanotechonology (nanotech), quantum computers, genetic engineering, improvements in ion thruster technology, high-temperature superconductors are just some of the technologies we cloud see in the next 25-50 years which would lead to development of the basics of space warfare.

Oh and nukes would still have some use - but not in stupidly powerful builds but rather in high electro-magnetic emission bombs for EMP and as cobalt bombs for punishments or terror attacks due to them turning wide areas inhabitable for centuries (now imagine a star ship threatening to bomb the largest cities on planet with them).

But it all depends on how realistic you want to be - I am usually am somewhere around half the way on the realism scale with most things being based upon technologies being already developed or that are scientifically plausible. Less realistic you get the more firepower your ships will probably have - more realistic you get, well at some point even FTL would be need to disappear.