By using these apparently insignificant symbols you make sure that the reader, in this case, your tutor, is going to understand your piece of work the way you want him to understand it. As a general rule, the longer the sentence, the more necessary punctuation symbols become.
The absence of any punctuation symbols gives a poor impression about you, the writer, but also it does not help at all if a sentence is ambiguous and there is no punctuation is in sight.
While you are working on your assignment you should carefully think about the punctuation you need. This is specially the case if you a run-on-sentence lover and you are not very familiar with the use of the most basic punctuation symbols. Also beware of the carelessly used punctuation symbol. Tiny as these symbols might be, their effect could be worse than expected if used in the carelessly used. Not only that, the choice of wrong symbol can change the meaning of a sentence altogether. Remember that worse than the absence of punctuation is the wrong use of punctuation itself. For that reason, it is a good idea to learn about the basics of punctuation before you start drafting your assignment. Once your work is completed is always a good idea to have someone go through it before you hand it in. Any written assignment should be carefully written and proofread for punctuation mistakes.
Emoticons or smileys are not considered to be punctuation symbols and are not used in a formal piece of writing.
Never write a comma between the verb and its object
The Australian National University Academic Skills & Learning Centre: