The best cycling routes will depend on what type of cycling you intend to do, your fitness level is, your goals for the ride, and what trails or roads are available. Mountain bike cycling routes will be limited to the trails that you are willing to travel to, while road cycling routes should be planned not only in terms of ability level, but also in terms of safety. It is not a bad idea to drive the route first to check for narrow shoulders and breakdown lanes, obstructions, stop lights, fast drivers, and other potential hazards.
Get a map of the trails or road systems you are considering for your cycling routes. Examine them carefully not only for distance, but also for elevation gain. Many high quality maps of mountain bike trails will feature topographical lines and indicators that will tell you how much climbing you will end up doing on your ride. If you are a beginner, consider easier trails with little climbing. If you are a more advanced rider, extend the ride or include more climbing. Road cyclists can examine a map for distance and elevation as well, though many road maps do not include topographical features that will indicate how much climbing will be included.
Road riders need to examine cycling routes carefully to ensure it is safe to ride on the roads. It is not too much of a stretch to say that some roads are in poor enough condition that a cyclist will want to avoid them. More importantly, a cyclist may want to avoid roads that do not have enough space on the shoulder for a rider to ride safely, roads that feature several stop lights, roads that are prone to high traffic or cars traveling at high speeds, and other hazards that may pose a risk to the cyclist's safety.
Regardless of the type of riding you will be doing, be sure to plan a route within your ability level; as you progress in your abilities, you can plan more challenging cycling routes, or even participate in organized rides. To start, however, it is a good idea to choose an easy route on which you can gauge your fitness and comfort levels. Non-competitive cyclists may also want to consider planning cycling routes that will allow them to ride through or past scenic areas, which can enhance the fun of the ride and give the rider opportune moments to stop, rest, and enjoy the view.