First, sector space should have a black background. There should only be stars and other really big objects (nebulas, black holes...).. They should be 3D objects rather than a texture. When going to warp, the stars should start to move and become streaks. When using impulse, the stars should not move at all.
When going to warp or out of warp, you should really get a feeling for the enormeous speed.
During warp, changing your direction should be slow. When changing your course, the ship should drop to impulse, head to the new direction and go to warp again.
Systems should not be visible, they are only small points at that distance. There should be a position reticle with the name maybe, but no visual object.
To set your course, you should use a nice galaxy overview map.
When something comes into long range scanner distance, it should pop up as a reticle and not as a visible object. You can then use a drop down menu on that reticle to aproach that object (if it's an enemy contact for example).
If you approach something with warp speed or it approaches you and you are near enough, it should automatically switch to the appropriate normal space/map.