Single engine taxi out burns no less fuel than two engine taxi at high gross weights.
Not true. A jet engine is more efficient at a higher power setting than a lower one. One jet engine burning 800 lbs/hr produces more thrust than 2 engines burning 400 lbs/hr.
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Other ways to save:
Try to minimize brake use during taxi. Don't move up in line right away if at all possible. Wait until you can move 2+ airplane lengths.
Land with idle reverse and let the airplane roll to the end of the runway saving brakes and fuel.
Consider taxing with one engine and no APU. Crossbleed to start the 2nd engine instead of starting the APU (this may or may not be more efficient depending on the APU and if your company is charge by APU cycle or not)
Cost index if available.
Fly shallow power idle descents. A 3deg idle descent is more efficient than a 4 deg idle descent. Staying high then coming down at 6deg with the spoilers is NOT fuel efficient compared to a 3deg power idle descent.
When you know your going to hold slow down now.
Know your min clean speeds to avoid putting in flaps too early.
Use flex / reduced power takeoffs.
Fly with an aft CG (if you can control that).
Tanker when it is economical.