Middle Voice

Who
  wants to   do what? 
    stem ending  
 I  βούλ   ομαι   καθεύδειν
 do you?   ἆρα   βούλ  ει   δειπνεῖν; (dine)
   he/she/it    βούλ  εται   ὁρᾶν τὴν ἑορτήν
 we  βουλ  όμεθα    ἡσυχάζειν (rest)
 do you?  ἆρα   βούλ  εσθε   διώκειν λύκους; 
 they  βούλ  ονται   ἀκούειν τὸν μῦθον  
 
All right, so "you want to ..." should really be βούλεσαι .
The σ was dropped, so then we had βουλε-αι.
But ε + α normally contract to η, so ε + αι will contract to ῃ
And ε + αι becoming ει is just a alternative formation,
or maybe just an alternative spelling because
η and ει were once pronounced the same.
But that doesn't apply to , there is apparently no  βούλῃ verb-form
Better use 'you receive or accept' instead (of δέχομαι)
 δέχει 
or  
 δέχῃ 

Your turn now to practice these forms, use the right half of your brain (pictures, sounds, smells, feelings). As far as "wishing, wanting" is concerned, that shouldn't be too difficult. A Greek-English mixture is fine, if it allows you to become really familiar with these middle voice forms: Maybe you βούλει strangle the teacher? Well, go right ahead - in your mind only, please - if that's what you really βούλει. You should come up with far better thoughts than that though.

Think you've had your fill of wishing but need some more practice. What about experimenting with the following:

We may need the infinitive forms as well:

  stem     ending    meaning 
  βούλ   ομαι    I want to  
  βούλ   εσθε    you all want to  
  βούλ   εσθαι    to want to  INFINITIVE
 
 γίγνεσθαι  to become old, frustrated, relieved, rich....
 δέχεσθαι  to accept, receive presents, guests, a laurel wreath
 ἔρχεσθαι  to come, to go all sorts of people come or go
 ἀπέρχεσθαι  to go away trains, planes, friends, we ourselves...
 πείθεσθαι  to obey children, wives, husbands, not always ( αἰεί )
 ἐγείρεσθαι  to wake up difficult, not possible, don't want to....
 λούεσθαι  to get washed, to wash for one's own benefit