Some cultures prefer slow-talking conversations. Words slither out, each with its own emphasis and pronunciation. The words are treasured for their meaning and elocution is a critical element in the delivery.
However, there are places and times when we find it necessary to rush through whatever we want to say. In this case words are shortened into sound fragments that are not grammatically correct.
For example, dropping the final consonants in words ending in “-ing.” I’m writin’ a letter, he’s callin’ his friend; we’re goin’ to the mall. Acceptable in casual conversation or when writing in dialect, but it is never acceptable in Standard English.
A huge mistake seen by learners is using “of” instead of “have” as an auxiliary verb. “Of” is a preposition that is followed by a noun or pronoun. “Have” is a verb that can be followed by other verbs. For example; I could have gone. You should have called. This is also true for could, should, must and might.
If this is hard for you, then avoid the use of those verbs altogether. Chose a verb that stands alone, expressing the emotion, feeling, action that you intend. I traveled all over Europe. You screamed at me. Bill tumbled down the hill.
If you believe that auxiliary verbs are necessary to your writing, there is a tip to ensure that grammatically correct English is used: skip “have” altogether and go straight to the bare form of the main verb. I could send an email. You should enroll in classes. Tim might build a rocket.
One more thing: I often see writers use “alot”. Please be aware that no such word exists. Instead use “a lot”. A lot of things happened on our trip. We bought a lot of souvenirs. Stan fell a lot when he was learning to ice skate.
These little tips will strengthen the finished product. I hope you find them useful.