1- When starting a new business, first you will need to choose a business structure. There are quite a few to choose from, and the type you pick is vitally important. They all have their own advantages and disadvantages. Here is a publication from the IRS on choosing a business structure.
2- Filing with the secretary of state is usually the next step when starting a new business. From this link you can register a new trade name or form a new business entity in Colorado. Here you may also search for available trade names to see if the name you have selected for your business is available. Registering your trade name will protect your right to operate under that name in the state your are operating your business in.
3- Another important step when starting a new business is applying for a FEIN or Federal Employer Identification Number. Here are the instructions for applying for a FEIN.
4- If you will be selling or renting any kind of tangible goods or property, then you will need to obtain a sales tax license from the state of Colorado. Here is the link for obtaining a Colorado sales tax license.
5 - Once you have your documents filed (or before if you need help) definitely visit the Colorado Small Business Development Website. They have many resources, classes, and informational articles to help people starting out with their new business venture.
6- S.C.O.R.E. is another organization that helps small businesses get started.
7 - Another valuable resource is the Colorado Business Resource Guide, which provides much important information for new business owners.
8 - Here are some tips from the SBA for writing a business plan. This is imperative if you are looking to get a loan or find investors. However, it is always a good idea to have one when starting a new business regardless.
9 - If you do need a loan, you might want to take a look at this page composed by the SBA on Small Business Loans.
10 - Here is another resource at business.gov that allows you to view many new business resources.