Clarification
I often see sentences like "Please contact me if you require any further clarifications." The word should be 'clarification'. Like the word 'information', it becomes countable when you are talking about specific pieces of clarification you need. In most cases you will mean the act of clarifying something, so use the word as an uncountable noun – clarification.
NB: It would be much better to say, "Please give me a call at xxx if you have any questions."
Clichés
Clichés (or platitudes) are things that have lost their sparkle, and often their meaning, through overuse. Examples of writing clichés are those old-fashioned terms like above-mentioned, enclosed herewith, please be advised, I am writing to inform you.
Clothing
Another uncountable noun, this word does not need an 's' on the end. Even though you can count the number of pieces of clothing, you should still use the word clothing without the s.
Compare to/compare with
When comparing things that are dissimilar, use compare to. When comparing things that are similar, use compare with.
For example:
My life has been compared to a soap opera.
US Congress may be compared with the British Parliament.
Comprise
We should not use the word of to follow comprise or comprises. The word literally means 'to consist of', so when using comprise we don't need the word of, otherwise we would be saying 'to consist of of'.
Contact on or Contact at
Both of these expressions are correct. Contact me on xxxxx is British English and Contact me at xxxx is American English.