I'll explain the usage of "どっち", "どちら", "どれ", and "どの" to you.
<Is Japanese really difficult? (Part.54)>
(A) どっち
(B) どちら
(C) どれ
(D) どの
(1) You can use "どっち", "どちら" for two things, and "どれ", "どの" for three or more things.
For example, there are an apple and an orange on the table.(one apple and one orange)
You can say :
(A-1) どっちが好き？
(A-2) どっちの果物（くだもの）が好き？
(B-1) どちらが好き？
(B-2) どっちの果物（くだもの）が好き？
In this case, you can't say:
(C-1) どれが好き？
(D-1) どの果物（くだもの）が好き？
When there are three fruits or more, (C-1) and (D-1) are correct.
Actually, "どっち" can be used for thee or more things in another case.
For instance, two people are chasing someone, and lost the person at the thee(four/five)-way intersections.
You can say: 「あいつ、どっちへ行った？」
(2) You can use "どっち" and "どれ" alone.
(At the store)
「こっちの赤い服と、あっちの青い服、どっちが似合うと思う？」
「ん～むずかしいな～」
「ねぇ、どっち？！」
(In the company)
「机の上の書類とってくれる？」
「え？どれ？」
(3) We use "どちら" with "様(さま)", "に", or "へ"(pronunciation is え, in this case).
・どちら様
どちら様ですか？
・どちらへ/に
どちらへ行くのですか？
どちらにいっらっしゃいますか？
