Grammar: Problems with Prepositions.
You may end a sentence with a preposition. Just do not use extra prepositions when the meaning is clear without them.
That is something I cannot agree with.
That is something with which I cannot agree.
Where did he go?
Where did he go to?
Where did you get this?
Where did you get this at?
I will go later.
I will go later on.
Take your shoes off the bed.
Take your shoes off of the bed.
You may look out the window.
You may look out of the window.
Cut it into small pieces.
Cut it up into small pieces.
Use on with expressions that indicate the time of an occurrence.
He was born on December 23.
We will arrive on the fourth.
Of should never be used in place of have.
I should have done it.
I should of done it.
Between refers to two. Among is used for three or more.
Divide the candy between the two of you.
Divide the candy among the three of you.
The word like may be used as a preposition and in informal writing, as a conjunction. In formal writing, use as, as if, or as though rather than like as the conjunction.
You look so much like your mother.
You look like you are angry.
You look as if you are angry.
Read more at http://www.grammarbook.com/grammar/probPrep.asp