Too informal, or perfectly casual?

<p>I'm kinda torn when writing my essays because I've been told to be casual, and in certain instances I want to use "I've", "don't", etc., but it seems that this might be too flippant or informal. Is it ok to use such (whatever the grammatical term for these things is)?</p>

<p>I use contractions in my essays and find no problem with it. If contractions allow your language to flow naturally, then by all means use them. I also like the following explanation from On Writing Well:</p>

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<p>thanks a lot</p>