The particular verb you choose and the way it’s integrated into the clause are important. As the basic principle, you want (other things being equal) to maximize your use of intransitive and transitive active verbs and minimize the use of transitive passive and linking verbs. Study these illustrations:
While you can modify this intransitive verb with an adverb, it takes neither an object nor a complement as part of the main clause structure. Structurally, it’s complete in itself, in that it has a subject and a verb (S-V), and it's pretty clear and direct.
I hit the ball.
This transitive active verb takes a direct object (ball) to receive the action (expressed in the verb hit) preformed by the actor (I, in the subject slot). The sentence is clear and economical because this transitive relationship (actor-action-passive recipient) moves directly through the sentence in the same way the reader reads it.
The ball was hit by me.
Transitive passive (using the recipient as the subject) has two main problems.
First, it’s wordy. The auxiliary (was) needed to render the verb passive, together with the preposition (by) needed to clarify the logical relation to the actor (me), increases the length by 50% with no corresponding increase in the meaning.
Second, the transitive relationship is now moving backwards through the sentence. The reader is moving left to right through the sentence, but all the action is moving back right to left. Several such sentences in a row will tire the reader; unless you really don’t know the identity of the actor or have some really clear-cut need to cast recipient as subject, stick with the transitive active. Recast The ball was hit by me into I hit the ball.
Crim is the tutor of his regular students.
In this clause, the linking verb (is) states logical equivalence between the subject (Crim) and the subjective complement (tutor). This structure is pretty direct, but it also has two problems.
First, this verb is DULL – it lacks motion. A whole page of these will put your reader to sleep.
Second, this verb choice offers too little economy: you’ve used your only main verb slot and filled it with a verb that, on a scale of meaningfulness from 1-10, rates about a 2. Better might be:
Crim tutors his regular students.
This choice gives a more direct and compact cast to the whole idea.