I’ve just written one of these myself!
Include a comprehensive annual staff survey including methods of travel and questions about which incentives would encourage them to give up the car etc etc, staff distribution in terms of residence/distance travelled etc. You can use this as tool to determine what measures you need to put in place.
Speak to local bus/rail companies to see whether you can get a discount scheme going for your staff
Speak to liftshare companies in your area – these can be quite effective also
Have you signed a section 106 with your local authority yet? If not then don’t until you are completely happy that you can meet your aims/targets
I would also conduct an offsite-onstreet parking survey as soon as you can to get a picture as to how you are affecting the local area and its something the LA will be very interested in.
Sorry none of this is in a clear order, just typing as thoughts are occuring : )