1) Supply more than one observation with the spot forecast request.
This will enable the forecaster to better understand how the weather changes over time for that specific area.
2) For a prescribed burn, provide a copy of the prescription to the forecasters.
This will let the forecasters know which parameters and what values are important to you. The forecaster can then fine tune that part of the forecast.
3) Don't hesitate to contact the forecaster directly if the forecast is going bad.
Forecasting the weather is a very inexact science and becomes even more difficult in complex terrain. Forecasts are seldom perfect, but when they are just plain wrong, contact the forecaster, explain what part of the forecast isn't working out, and request an update. Also, you probably know more about micro-meteorology and wind flow over the terrain than you give yourself credit. Explain to the forecaster what you are observing, and what you think may be the cause.
4) Provide feedback to the forecaster to let them know what was forecast accurately and what wasn't. If you never let the forecaster know how they are doing, they will have to assume that everything occurred as forecast. This could cause them to routinely inaccurately forecast certain parameters. Feedback is especially helpful to the forecaster if you will be requesting a spot forecast for the same area over consecutive days.
5) Invite a forecaster from the National Weather Service to a prescribed burn.
By actually observing a prescribed burn, the forecaster will gain a better understanding of fire behavior and how his forecast is used.