To find an apartment in Greeley, your best bet is to look during the summer months. Availability goes up from about June through to August, so if you can arrange to do the majority of your apartment searching during that time, you will position yourself for the most possible success.
Set up as many apartment viewings together as you can, and actually make a trip to Greeley before you relocate. Trying to find a place over the Internet is difficult, and can leave you victim to one of the many rental scams out there. Always meet with the landlords in person, and never pay any deposit money until you have viewed the apartment in person.
Getting around within Greeley is straight forward, especially if you're mostly concerned with getting to the University of Northern Colorado. The Boomerang Bus connects the city to UNC and provides quick and efficient transportation for students. There is also an ongoing initiative by local government to get a higher number of operational bike lanes in the city.
If you've got a sweet tooth, head downtown to sample the wares of the local Ice Cream shop or one of the several gourmet sweet shops and bakeries. The Greeley Mall is a popular local hangout with most of the familiar mall stores from across America. Downtown is home to most of the town pubs, and there are also several local craft breweries that the new generation of beer drinker should enjoy.