The best known use of runes still is divination. Frequently people have the misconception that runes will divine the future, as if the future would be written in stone. They're far better used as a means to show what can happen if a certain path is taken and help you decide what to do. In the end, the decision is still yours and the outcome is entirely your responsibility.
As all other divinatory systems, the runes are a focus through which your higher consciousness communicates with you. The better you know the runes and the more in touch you are with your higher consciousness, the better the results will be.
When should the oracle be used:
The oracle can be used whenever you feel the need to do so. Specific times or rituals are strictly optional to put you in the right frame of mind, so if you don't want to adhere to formulas, don't use them. If you want you can restrict to important questions solely, but as divination also takes practice I suggest using them when you feel the need.
What questions can be asked:
Whatever is on your mind. Refrain from question that lead to a direct Yes or No. Also, don't ask suggestive answers like "When will I win the jackpot in lottery?" as you then suggest that this will happen. Further, don't ask too vague questions like "how can I be happy?". Question like that are too vague to get any precise answers and only show that the questioner doesn't know what he wants to know. On the other hand, the question shouldn't be too precise, eg "What will happen on 26.8 in Oxford Street?".
What rune-set should be used:
There are many pre-made sets available in online stores and bookstores. However it's better to create your own set. It may not look as good as say the crystal rune set but it's personal.
Bright and Murk:
Bright refers to the upright shape of the rune. In regard to the question it usually means something constructive, helpful or positive.
Murk refers to the upside down rune. People frequently make the error and see it at once as something infinitely negative. It's better to see the murk runes as an indication for a crucial situation.
The 24 runes of the Elder Futhark are explained here.