Here are a few points from those who have previous gone:
Temperature
People are always concerned about the heat when they go for Hajj. Usually, people stay indoors during the hot afternoon sun and go to pray at the haram in the evenings and in the morning (sometimes through the night.) Know the average temperatures in Makkah and Madinah around the time we are going for Hajj.
Crowds
Our group leaders know the peak times for performing the wajabats and they will advise us on when to do our tawafs and when to hit the shaitan. Those who are doing the taqlid of Ayatollah Sistani are able to perform some wajibats with more flexibility in timing. Our group leader will therefore advise you on these timings so we can take advantage of these non-peak times with a lot less rush.
Bathrooms
We will likely have to use an Eastern toilet sometime during your Hajj. Most houses or hotels have both Eastern and Western toilets or just Western ones. In Arafah and Mia there may only be one Western toilet if at all. Also in areas outside of the hotel like in the haram, there may be a lot of water on the floor in the washroom area. Be prepared. Having shoes that are waterproof or easy to hose off, also helps.
Accommodations
In Mina we will be staying in tents. They are big white tents that accommodate a large number of people. The HAS usually upgrades their basic tents to have private tents with mattresses, blankets, pillows, air conditioning, etc.
Preparation
We want to make the most out of your Hajj, afterall this can be a once in a lifetime opportunity. There’s a lot of things to buy, to learn, to read, etc. and it seems like the days of the actual Hajj just fly by. Before you know it you will be on the plane returning home. Read as much as you can about the history of Islam, the rules for Hajj, and about the life of the Prophet and Imams you will be visiting.