Learn how to pray Salatul Janaza.
Understand the meaning of what you recite in salah – good source here.
Make a will before you leave.
Sincerely repent – pray 2 nafl and make tawbah.
Ask your family and friends to overlook and forgive your shortcomings.
Print a dua list. Ask your family and friends for dua requests since you will be in the holiest of all places on the best day of the year – Arafat. You can make a quick form on google forms and then email it out to all your acquaintances.
While stepping out of the home, offer the following supplication: Bismillaahi tawakkalthu ‘ala Allaahi laa hawla walaa quwwatha illaa billaahi — (I start by the name of Allah; in Allah, I place my trust. There is no strength (to do good) nor power (to resist evil) except with Allah).
Learn and appreciate the history of Makkah and Madinah. The most important advice we can give you is to really learn the seerah of the Prophet (S) to appreciate the beauty of the place you are about to set foot in. This will make your Hajj more special and memorable. The difference between an average Hajj vs. an OUTSTANDING Hajj is this point. The 3 best sources that come to mind are:
Watch the Omar Series on YouTube, starting here. You will visually see Islamic history from the point of view of Omar ibn al Khataab (3rd Caliph). The series is action-packed, captivating, and reportedly the biggest Arab production ever. It’s 23 hours long but totally worth every minute.
Listen to Yasir Qadhi’s seerah on YouTube here. It’s over 100 hours of in depth detailed knowledge, with great connections to modern day society.