little, few ,not enough攪不清楚

a few and few are used before plural nouns.
a few means 'a small number' : It will take a few minutes. | I've got a few friends who live nearby.
few means 'not many'. It emphasizes how small the number is. It is mainly used in writing or formal speech : Few people would deny her talent. |He has few interests outside his work.

a little and little are used before uncountable nouns.
a little means 'some, but not a lot' : We still have a little time left.
In spoken British English, it is more usual to say a bit : 'Are you tired?' 'A bit.' |I've got a bit of money left.
little means 'not much'. It emphasizes how small the amount is. It is mainly used in writing or formal speech : There is now little hope of success.
In spoken English or informal writing it is more usual to say not much : There was not much milk left.

enough('Not enough' is the negative of 'enough' .)
as much as is necessary; in the amount or to the degree needed
Is there enough cake/Are there enough cakes for everyone?
There are 25 textbooks per class. That should be enough.
Have you had enough (to eat)?
I know enough about art to recognize a masterpiece when I see one.
He's tall enough to change the bulb without getting on a chair.

2009-10-29 16:37:59 補充：
enough comes after adjectives, never before : This one is big enough (NOT enough big). | Is it warm enough for you?
enough usually comes before nouns : We haven't got enough time. |Are there enough plates?

2009-10-29 16:38:02 補充：
Sometimes people use enough after nouns in particular expressions, but this is not very usual : There will be time enough for that later.
!! Nouns used with enough must be plural or uncountable, never singular : There aren't enough books (NOT enough book). | She has enough money to live on.

2009-10-29 16:40:09 補充：
few是用於plural nouns之前 解作不多(not many)
little是用於uncountable nouns之前 解作不多(not much)
enough可用於plural nouns或uncountable nouns之前 解作足夠(not enough則是不足夠)
enough也可用於形容詞之後

詳細的內容請看上面