Well Andy,

The first thing before trimming is to have a good reference. I use an excel sheet to record the weight of the kit elements when they arrive to me.
You can have a look here at my Me262 load sheet:
http://www.geohei.lu/olin/data/model...eet%20P-60.xls
Every single component can be listed and compared.
You will be able to see what component is dragging the plane on the heavy side...

Then it is all a matter of how much time you are ready to spend to trim the aircraft.
One very easy way to loose weight without spending much time is to choose carefully the components.
Here is a list of great weight savers:

Lipo batteries ( some are significantly lighter than others )
Weatronic receivers
Multi-fonction valves like the Air Power EV5U/ EV5U pro systems

The most significant impact of the weight reduction is the stall speed/loww speed handling of the aircraft.
A lighter aircraft will stall at a much lower speed and thus have a lower approach speed ( 1,3 Vs )