Hk airport is definitely HUGE! Make sure that there is ample time in between your transit flights as navigating within the airport can be very stressful! HK people are not known be courteous nor helpful. When you book, make sure you request airline assistance upon arriving in HK. Am assuming you are on CX flight, CX is a very efficient carrier, when my father travels alone, I normally request wheelchair assistance, not because he needs it but he is assisted all the way to the receiving party. When you check in, make sure your luggage is straight through to last destination and if possible, you have the boarding pass of the HK-Doha leg because this is another concern once you get to HK. Another point to consider, do not bring several handcarries so that you dont get slowed down by dragging your things from one end of the airport to another.
Cheers, just read the signs and stay smart, youll survive!

Happy trip!