I believe the most difficult part after obtaining all the licenses and certificates is finding the right atmosphere for your experience. Also you have to deal with the different policies, regulations and ethics. You will be working 12 hour shifts for the most part and dealing with various degrees of psychological decencies from various backgrounds. The salary and the job duties does not match but you will have great opportunities to network and change lives. The most difficult part I would say is to not get too emotionally attached to your clients and not to let the job environment stress you out.
I wish you the best on your journey.