Usage of Reflexive Verbs

Question

I understand how they are formed but I don't understand when they should be used and when they shouldn't be used. I don't understand how to determine whether the verb should be reflexive or not and in what type of sentences you should use it, could you please clarify this for me. Thanks in advance.

Accepted Answer

You don't really have to determine whether a verb should be reflexive, you just need to memorize whether one is or not.  
Example:  to brush one's teeth = reflexive  so I need both the subject pronoun (Je) and the reflexive pronoun (me) --   Je me brosse les dents.  
to go to bed = reflexive  so I need both kinds of pronoun again -- Tu te couches.
to eat = NOT reflexive  so I use only a subject pronoun before the verb  -- Je mange deux tartes.
Each time you learn a new verb, if it is reflexive, you will notice "se" in the infinitive form:  se brosser,  se coucher,  etc.  If it does not have that "se" in the infinitive form, it is not reflexive.  (I'm speaking generally here, as you progress in French, you will find some other verbs can be used reflexively, but do not worry about this yet!) 
The first reflexive verbs you will learn are those for taking care of oneself -- a few more not mentioned above:  s'habiller, se doucher, se laver, se casser.