Now on to Commandment 3. Where’s the fluff? Sadly, our awful sentence is all fluff. It puffs itself up with wordiness that communicates almost no concrete information. Unless you’re doing laundry, you’re not allowed to fluff. The best way to cut the fluff is to realize—and admit—that your writing is wordy. In your rough draft you’re allowed to write down unfocused ideas and to ramble a bit. But your final, polished version must be much more concise. Put aside your draft for a while and then cut it down—perhaps way down. Examine every phrase and shorten, shorten, shorten.
Advice: If your 'sentence' is a dependent clause, or it doesn't contain both a subject and a predicate, then it is not a proper sentence. You can often detect fragments if you read your writing backwards sentence by sentence, . from the last sentence to the first one. You can usually correct a fragment by connecting it to the sentence before or after it.
Good writers, who have a full understanding of the sentence, occasionally choose to write a sentence fragment. So you may see sentence fragments in the fiction or even some of the non-fiction you read. As an ESL student, however, you should avoid fragments (except when writing your own creative stories).