When you turn 18, you realise there is a whole new world of possibilities waiting for you. One of those possibilities includes "leaving the nest" where you have been raised, and which you now feel it is time to exit. Moving out at 18 can be done in an almost flawless manner if you prepare.
Start saving money early if you know that your ultimate goal is to move out when you turn 18. Even having a part-time job that allows you to save some cash will help you achieve this goal, since you have few costs while you're living at home. The trick is to use some restraint in buying so the money stays in your possession until it is time to move.
Secure a somewhat steadier source of income when you are ready to move. This is especially true if you will be paying your own rent. Your job does not have to be the best, but at least make what is necessary to cover your needs at the beginning.
Share the burden. Getting a flatmate will allow you to split costs and possibly move in with someone you like. Make sure that he is responsible and will pay his half of the rent. Finding a flatmate your age will also ensure that you have some things in common. Sharing costs with a responsible flatmate will allow you to stretch your money further instead of using it all on essentials.
Be frugal. Since this will be the first time you are on your own, resist the temptation to have the best and the newest. Find an affordable living space that is within your budget, and only purchase new items when you absolutely have to. Furniture can be found affordably in second-hand shops, charity shops or at the Salvation Army. You could even rent furniture. Sacrifice cable and satellite TV for a while if your budget is too tight for it in the beginning, along with other services that may not be necessary for your initial venture into independence.
Consider joining an all-expenses-paid organisation. There are many that allow you to volunteer in exchange for living quarters and education in a skill. Some of these organisations include the military and religious charities. These programs provide money (in some instances) and living arrangements if you sign a contract for some type of work. However, they often limit personal freedoms while you are going through the training -- and in the case of the military, contracts are specified for a number of years.
Ask your relatives if they have any old belongings or furniture that they can give you. You may also acquire more than one flatmate to share costs even further.
Inspect all living spaces in person before you sign a contract to move in. Don't take anyone's word about the condition of the place, regardless of the price. Have a backup plan or money saved in case one of your flatmates bails out on you.