Successful long sentences
Vary the rhythm of your writing to make it pleasurable to read.
Active and passive voices
The passive voice is useful in certain contexts but use the active voice when you can - it's clear and concise.
Hunt out the zombies in your writing
Switching nouns to their verb form can energise your writing.
Keeping subject and verb together
To make your writing clearer, try to bring the verb close to the subject of your sentence.
Cut the waffle
In academic English, short sentences and paragraphs are often clearer, more readable and more effective than long ones.