1) Choose the most important aspect of flooring for you. Is it durability? Is it price? Is it availability? Is it aesthetics? Rank those things in order of importance to you. This will help you to determine what kind of floor works best for you. Floors withhigh durability tend to be higher cost, and a specific style might lock you in to a specific price point as well. On the other hand, if we can be flexible about the order of importance of each aspect, that will allow you the most options based on your project.
2) What is your sub-floor? Some flooring (solid wood for example) generally cannot be installed below grade (in a basement) or on concrete. If you have a plywood sub-floor you will have just about any option available to you. Oriented Strand Board (OSB) and particle board also restrict you to a floating floor installation. There can be some exceptions to every rule, but this is definitely something you need to know BEFORE you buy!
3) What room(s) will your new flooring be installed in? Some floors (hardwood, bamboo, etc) are not recommended in bathrooms. Some other floors are not the best in an entry way (cork flooring) where your floor needs to be the most durable. Some floors resist color change due to UV exposure better than others (stained floors - not natural color floors).
4) What kind of durability do you need for your project? Pets will be able to scratch the very best finishes on the market. Dropping a can of soup that lands on its edge will leave a mark on the hardest Janka Scale rated floor that you can buy. Instead find out what floors will work best for the area you will install it because a hallway and an entry way will take alot more abuse than a bedroom. Additionally if you plan to replace your flooring or to move out in 3-5 years then you should be more interested in how to upkeep your floor and how to protect it because your flooring should be able to last that long, its just a question of how it will look at the end of those 3-5 years! Just like a car, if you take care of the floor better the less scratches and dents it will get!
5) How do I choose the right look for my floor? Flooring, especially natural flooring, gains much of its beauty through color changes and pattern changes that nature gives wood, cork, bamboo, etc... However if you want to have a more consistent look for your flooring you should choose a floor with a "stain". Stains add a base of color that helps reduce the "highs and lows" that come with a natural tone floor. Stains also act as a UV inhibitor, so the darker the stain the better the protection against UV color change!
6) How helpful are samples? Samples are a great way to get an idea of what your flooring can look like, but keep in mind that all floors (once installed) are viewed from a standing position, and on a much larger scale than one 6" piece that you get as a sample. Try to imagine both the lightest color and the very darkest color in the photos online, and in the sample as an entire plank mixed in with each other all across your floor. Floors are natural and so having color variation is expected and hopefully enjoyed! If you crave a more consistent look, be sure to examine a floor with a beautiful stain applied to it.