Is there any magic items or spells that can increase the accuracy of where you end up when using Plane Shift either by spell or magic items that function the same way?
I think it was in 3e there was a magic item that acted as a beacon that allowed you to plane shift to it with perfect accuracy but I don't recall the source or whether anything was ever made for pathfinder that functions the same.
The only method that I know of is to create a demiplane to use as your home base. Cast Plane Shift to get there -- the inaccuracy of the spell does not matter when you are shifting to such a tiny plane. From there you can eject yourself and your party to the Material Plane at the location you created the demiplane from.
If you're high enough level and have money to burn you could use wish instead of plane shift.
* Transport travelers. A wish can lift one creature per caster level from anywhere on any plane and place those creatures anywhere else on any plane regardless of local conditions. An unwilling target gets a Will save to negate the effect, and spell resistance (if any) applies.
Planar Wanderer feat lets you reduce your error to as little as 5d6 miles. It has a feat prerequisite, though.
Dimensional Occultist Witch? Probably not practical but...
Mythic plane shift, if that's allowed, will bring you to an exact location if you've been there before.
What Seannoss said.
Otherwise, Gate is the most accurate and far-reaching of your travel spells.
On lower levels you can bring scrolls with teleport and use UMD...if you have no arcane caster in the party anyway. A somewhat slower method is to use windwalk, which grants 60 mph, to get from the point of arrival to the true destination.