Quote Originally Posted by Yoda View Post
Also, Penguin said in chapter 12 that хотеть is generally used with perfective to express to want to do something. In addition, it uses as an example:
я хочу пить = I'm thirsty
я хочу выпить = I want to drink (alcohol)
So I'm lost. I shall use выпить or пить ?
Хотеть пить and хотеть выпить (when used without an object) are fixed expressions that mean, respectively, "to be thirsty" and "to want to drink alcohol". You should just remember them as is.

What about perfective/imperfective after хотеть in general, perfective means that you have intention of doing something. The emphasis is on "doing".
And imperfective means that you talk about your "internal state of wanting/wishing". The emphasis is on "wanting".
For example:
Я хочу полететь в Москву. = I want to fly to Moscow. = I want to travel to Moscow by plane.
Я хочу летать. = I wish (to be able) to fly.
Я хочу выпить чашку чая. = I want to drink a cup of tea.
Я хочу пить. = I wish to drink. = I'm thirsty.

I think, хотеть + imperfective is primarily used with verbs пить, есть, кушать, спать, гулять in the speech of adults. That construction is more common in the speech of children.