Talk to your manager first
Often, issues can be resolved by bringing your concerns to your manager first before even looking for a new position. You may be pleasantly surprised at the outcome, and it will save you the hassle of trying to secure a new position elsewhere. If your manager cannot or will not address your concerns, then at least he will feel that you have approached the situation in a professional manner and that you gave him the opportunity to work with you before you started looking elsewhere.