Check travelling times, you do not want to be late. Some employers have a particular dress code. If this is likely to be the case, ask in advance for guidance so you can dress appropriately on the day. Think about the questions you may be asked. If the job requires particular technical knowledge or skills, brush up on them.
Many jobs require good communication skills.
This is easier said than done and can require a great deal of thought. You may be asked to give a brief presentation, prepare it well and make sure you stick within the stated time-limit. Bear in mind that the person showing you around or having an informal chat with you will almost certainly be giving feedback to the interview panel. An interviewer will look at how you view your skills and experience. You should turn them into advantages or benefits for the employer.