Continuous tenses describe a continuing action in the past, present or future: "I was waiting for you, I am waiting for you, I will be waiting for you." The most common error occurs when we use present continuous describing an action that is still occurring: "I am waiting for you for hours." We should use the present perfect continuous: "I have been waiting for you for hours."
A second common error is the overuse of the perfect tense, a verb with a helper -- "he has waited" -- in place of the simpler past tense. "He has waited for you for hours" is more accurately stated as "he waited for you for hours."
Another common error is the use of future tense in a subordinate clause while the main clause is imperative. An imperative usage occurs in "I will wait for you." If the subordinate clause is future tense also, it is in error: "I will wait for you until you will come." The correct sentence uses the simpler present tense: "I will wait for you until you come."