Living in the mountains is beautiful and gardening is even more so (to the gardener). Like any location there will be things to learn to succeed and errors made in the learning process. Dedicated gardeners expect to put time, energy and money into their project. Determining which plants are suitable starts off with observation, education, and some trial and error.
Observations
The best way to quickly find out what might grow in your yard is to look at what others have established in your area. All due diligence has been done in a successful yard; climate, exposure, soil, moisture, etc. If the neighbors can grow it, you might be able to also. (Neighboring gardeners have discussed among themselves of why someone can grow one thing and the other cannot.) Local vendors and growers are also savvy to what successfully lives and can advise you and/or troubleshoot about what to plant.
Research
If you browse catalogs or books for plants(s) and ideas, know the USDA Zones. Plants are classified by their hardiness to minimum cold temperatures. Using the USDA Hardiness zone map, assume we live in Zone 4 (Zone 3 for higher elevations. Some information sources that are not Colorado based use their own standards and can be confusing. It’s best to stick with Colorado based information and a few great resources are Colorado Nursery & Greenhouse Association booklets and Colorado State University Extension websites.
In your search for information make sure you know what you have to work with; i.e., know your site. Knowing the site helps guide the plant selection. Specifications that matter are: elevation, hours of sun exposure, micro niches, source of irrigation (if any) and soil condition (porosity, water retention, nutritional yield). Trees that thrive back east may not like the elevation where you live. If the soil is to be unaltered, then the selection will be geared more towards natives from a similar habitat. (Native willows would not thrive on an exposed mountain top, unless there’s a natural spring.)
Trial and Error
Once the right plants are in place they require maintenance. Even native installs need a little nurture to establish, especially in drought years. Exact matches for the site may be dug under by ground voles or suffer snow rot. Foraging deer are a serious threat to newly installed landscapes. If they have a browse habit through your proposed area, you might try some deterrents before investing in the ornamental fodder. There are many lists of plants that the deer don’t like, but they’ll taste what they want when you’re not looking.
There’s a difference between thrive and survive! Just because the plant is listed for your area, may not mean it likes your yard. Some things may have to change and the last thing to change may be choices. Every garden is an ongoing project and initially it’s driven by trial and error. Once you’ve found selections that do well, add more!