Most people will be impressed by what you say, not by the complex way you say it. Keep your sentence length down. If you keep most of your sentences short, you stand a better chance of being understood by your readers. You will probably make fewer grammatical errors. If sentences are too long, the meaning becomes jumbled and obscure.
Readers have difficulty in understanding long sentences.
They often lose the thread halfway through and are tempted to give up. An average sentence should be no more than 15 to 20 words. If you find you have written a sentence that is too long, go back over it and break it into smaller ones. Cut out unnecessary words and phrases. Make only one main point in a sentence, with perhaps one or two related points.