Click Legislative Process for an excellent description of how a bill goes through the legislature.
After a bill is introduced, contacting legislators in the committee to which the bill has been assigned is the best way to influence its outcome. From the Legislative Process document linked above (emphasis added):
"Committees are often regarded as the workshops of the General Assembly. All bills are sent to a committee -- referred to as a committee of reference -- immediately following introduction (first reading by title). The Speaker assigns bills to committee in the House; the Senate President makes the assignments in the Senate. The details of bills and resolutions are carefully analyzed at committee meetings. It is at these meetings, which are open to the public, that interested citizens express their view."
Because hundreds of bills are considered each session, you will have the most influence if you either testify at the committee hearing or contact members of the committees at thetime the committee is considering the bill.
To find out the current status of a bill, go to leg.colorado.gov on the internet. Follow the instructions given in the Look Up a Bill page of this website to get to the detailed bill information page for your bill. Scroll down below the Bill Text button to view the status of the bill. The Bill History tab will tell you where your bill is currently.
Contacting a Legislator
You can contact a legislator by phone, email, fax or visiting in person. It is the most effective to actually talk to the legislator. After introducing yourself and stating which bill is of concern to you, ask the legislator how he/she intends to vote on the bill. This is an expected question and saves time for both of you. If the legislator is already planning to vote your way - thank him/her! If they have no opinion or do not agree with you, politely present your arguments.
If contacting in written form, it is more effective to state your opinions in your own words. Don't send a form letter - it won't be read.
Either in written form or in conversation, it is more effective to be specific. If you have a suggested change - specify where in the bill and what the change should be.