The worst thing you may be confronted with is to go for an interview badly prepared. Prepare for the questions they are likely to ask you, as well as the questions you would like to ask them. On the day of the interview, leave much earlier to avoid any chance of getting late. No one will accept your excuse for being late, however it may be due to reason beyond your control. If you are unavoidably late, offer a sincere apology just once, and then let it drop.
Many people pay less attention to what they wear on the interview.
Never ignore the possibility that every large company has its own dress and grooming code standards etc. If you expect the interview to last several hours, plan to wear clothing that will look neat all day. If it's raining, protect your outfit with reliable rain gear. Do not, under any circumstances, allow yourself to appear disheveled. You need to learn to appear as competent, it does create an atmosphere that is conducive to success.