Have an idea of what area of the hospital you would like to be an extern at. You aren't guaranteed a position in your area of choice but it definitely helps if you do know and want to pursue a specific route. They ask you top 3 MLH campuses and top 3 areas of interest
get your resume ready and professional looking- have highlights of your accomplishments, experience, education and bring multiple copies with you to the interview. They interview you in pairs usually so always have a few copies to give out and one for yourself so you can follow along with where they are referencing incase you get nervous.
Start asking clinical instructors for letters of recommendation so you aren't scrambling at the last minute when everyone else is also asking for letters. MLH requires 5 recommendations from previous bosses, clinical instructors, other professors peers, and they send them an email to complete an evaluation.
There is a video interview before an in person interview so start becoming comfortable talking to a webcam, practice just talking to yourself running through stories that highlight your experiences so far so you become comfortable with how you present yourself- highlight personal skills, characteristics, one patient that has greatly affected how you practice nursing, why you want to work at Lankenau vs other MLH sites
Smile! The video interview is definitely nerve wracking to have to answer a question in 30 seconds but take it slow, and think about what you want to say. The in person interview is much easier because you are talking to a real person, and its more natural.