Determine the time of the verb. For example, decide whether it is an action that took place in the past, one that is currently taking place or one that will take place at some time in the future (past, present or future, respectively).
Decide whether the action is passive or active. Passive actions are done to the subject, whereas the subject performs the action with active verbs. For example, "The president considered the bill" is active, whereas "The bill was considered by the president" is passive because the bill is the subject, being acted upon by the president.
Once you have the tense and nature of the verb, determine its form. The forms are simple, progressive, perfect and perfect progressive. "The president considered the bill" is simple past. "The president was considering the bill while Congress was in session" is past progressive. "By the time Congress reconvened, the president had considered the bill" is past perfect. "Before the budget cuts, the president had been considering the bill" is past perfect progressive.
Determine the number of the verb, meaning whether it is singular or plural. For example, "The president considered the bill" is singular, whereas "Presidents consider all bills passed by Congress" is plural.
Once you have the tense, nature, form and number of the verb, you can insert it into a sentence along with any helper words as necessary. For example, in the sentence "By the time Congress reconvened, the president will have considered the bill," the phrase "will have" is a helper phrase that clarifies the form of the verb, which is future progressive.