Know what the employer is looking for:
Before deciding to go for an interview it is desirable to know what the employer is looking for and up to what extend you are fulfilling their expectation. If your profile and experience does not fit for the job for which you are invited, avoid such interview.
Prefer formal dressing pattern of your region for an interview. There is no hard and fast rule about dress code, but your dress style should be one widely accepted as suitable for your job function.