Well, there is a lot of "noise" in both the physical and non-physical realms. Think of an old car radio and how it needed to tune into one station to hear a song clearly but as you dialed between stations, you'd hear a lot of static or even crossed signals from several stations.
It's similar to tuning your psychic sensitivities. Some people are very clearly tuned into one dimension using a particular clair while others are strong in several.
There is much to know but the very first step before proceeding is protection. After that, develop a strong practice of meditation. Then...decide what your purpose is for using your abilities and go in the direction you feel compelled to follow.