(This is based on the old wargame Starfire... but don't bother providing answers based on newer versions of said game.)
Spacecraft travel by inertialess drive -- that is, beyond mere reactionless drive, it conveys a speed rather than an acceleration. Many warships are capable of 0.1c. Smaller ships have a turning radius at that speed of about 1 light-second. There's a minimum practical size for this drive, so fighter/shuttle/etc-sized ships have to use a different drive, even faster but of much less endurance.
A long-ranged weapon has a range about 10 light-seconds. Rates of fire are comparable to naval warfare. At close range, a ship optimized for close-range combat can incapacitate a similar ship in one volley. Even at longer ranges, battles are decided within minutes.
Known space is connected by a natural(?) network of "warp points". Let's say they're roughly planet-sized, so it's impractical to build structures enclosing them. The critical thing is, you can't see through them or send radio through. Given that only ships with the inertialess drive field can survive passage, I can guess the warp points scramble up all unprotected matter and energy that goes through.
A typical star system has from 1 to less than 10 warp points. The reason I highly doubt they're natural is their positioning. They normally lead from one solar system to another, not into interstellar space. Multiple warp points in one system will very often be closer together than pure chance, usually light-minutes or even less apart. (There's one known warp point in the dreadfully inconvenient situation of having one end inside the photosphere of a red giant, but that location could've been convenient back when the star was on the main sequence... But I digress.)
Since the civilizations of this setting haven't invented an FTL drive on their own, I can assume they don't have FTL communications or sensors.
Now, what does warfare look like?
Things aren't going to look like WW2 on a strategic scale (contrary to what Starfire suggests). For example, convoys won't exist, because wartime trade routes simply won't pass through hostile territory. Within your own empire, you can move ships between systems unobserved by the enemy.
The only way to know what's in a system is to send a scout ship through the warp point and have it return. The problem is, in any system that's been inhabited for any time, all warp points are mapped. You can station ships or bases near any warp point leading to hostile territory and be ready to blast any scout that comes through.
So then the only way to expect to survive is to send a large fleet through without scouting, concentrating your forces to be greater at that point than the average defense you expect. So if the enemy has equally distributed their defenses among the possible attack routes, you can always expect to win. In a warp point assault, there's almost no room for tactics, as ships start at close range.
Or do they? Is it best to put your ships close to the warp point? It's the fastest way to kill any weaker attacker. Against any stronger attacker, it guarantees your whole defending force will be wiped out, as there's no chance to retreat.
And if you move a large fleet to attack at one location, your enemy can deduce you're weakened elsewhere, and it's the best time to launch an attack of their own. News can travel fast within your own empire. Something the game didn't show but that I can deduce will exist are communications relay ships that bob back and forth through warp points. With these and with speed-of-light communications between warp points that are often very close together, news can often be many systems away within minutes.
But if strategy then becomes based on moving big fleets around, most systems won't have effective warp point defense most of the time, and it again becomes possible to send smaller scouting forces...
In open space, you can't force an enemy to battle, so battles can only occur around fixed locations, IE, planets and warp points. And will even planets be important?
Tactics in space, with no cover and no meaningful terrain except those few fixed points, revolve around controlling the range. In a warp point assault, the defender controls the range. In a planetary assault, the attacker does. This suggests warp point defense is much more effective.
Is it ever worth mounting weapons on a planet? They can only defend that planet from attack. They can't prevent an enemy fleet from bypassing the planet to another warp point.
Do the longer-range weapon options have much use at all? In open space, the longer-range weapon essentially guarantees victory, but warp point assaults can start at close range.
Because fighters exist that can't transit warp points on their own, carriers exist. This is another case where warp point defense has the advantage: even without fighters of your own, you can (hopefully) destroy a carrier before it can launch fighters. So are carriers actually a worthwhile concept?
So, long-term, what are the prevalent attack and defense strategies in this world where you can never have meaningful information on where the enemy fleets are?