@Michael Calvey so where to start.
1) Colorado laws have changed and there are strict requirements that must be followed with severe consequences ($$$$) if you don't. Too much to cover in this reply. I will cover the ones that come to mind in reading your post. There are some exceptions for owner occupied properties so make sure to understand if the exception fits. I don't know the exceptions since they don't apply to my business. I own more units than qualifies for the exception and I don't live in any of my rental properties.
2) 3x rent is illegal in Colorado now. Colorado law says landlords can't reject applicants for income if they make more than 2x rent on a monthly basis. Yes 2X. It's crazy and clearly legislatures have no clue about the rental business but it's the law.
3) Colorado now requires that a landlord cannot reject applicants for being felons if the felony is older than 5 years ago.
4) Colorado now requires that landlords cannot reject applicants for being evicted if the eviction was more than 7 years ago.
The most important is: Write down your criteria ahead of time and do not deviate from it. I will repeat. Write down your criteria ahead of time and do not deviate from it. If you get it wrong correct it for the next vacancy but hold the line for this one. Adjust price but not the criteria mid stream. The pull will be to bend the criteria when you are desperate and it NEVER ends well.
The marketing advise is the best. Most exposure and quality ad is very important.
As other have said. Call and check references. Verify character of folks. Do they do what they say and pay their bills.
I have heard the car thing a lot over the years but it fails to cover whether or not they pay their bills. I had an applicant with a impeccable Mercedes that multiple accounts in collection. I don't know how they would have been as tenants as I didn't rent to them.
The bottom line is ... A vacancy is a blessing compared to a bad tenant.