Going to an unfamiliar place is difficult enough, but when it's filled with crowds and new sights/sounds it can be overwhelming. If you are not familiar with Disneyland, I would recommend that you sit down with a map of the park prior to your arrival. We also had our younger children watch videos of Disneyland on Youtube so that it would not be completely unfamiliar. I created a social story for our son who has autism. You can find that video here:
We recommend downloading the Disneyland app seen below onto your phone prior to your arrival also. It will give you park hours, showtimes, wait times for attractions at Disneyland and California Adventure, locations of characters/dining/shops/restrooms/guest services, as well as you can link your pass to get FASTPASS vouchers loaded directly on them.
We are naturally early risers since our children wake up early every day. That is very beneficial when visiting Disneyland. Get to the park early and beat the crowds! We have found that visiting the park opposite of the one offering the "Early Morning Entrance" is a best bet also. For the more popular rides, you will want to get your FASTPASS vouchers first thing to ensure that your ride time isn't at the end of the day. If you are traveling with a child who cannot ride and need to have 1 adult wait off the ride with them, you can ask for a rider switch which will allow the adult who was waiting off the ride to gain entrance through the FASTPASS entrance once the remainder of the party has exited the ride.
If you are traveling with a guest who has a disability, you can check in with guest services at City Hall or any green umbrella throughout the park to have a DAS (Disability Access Service) added to their pass. This will allow the disabled person and their party to obtain a return time for that attraction. This is helpful as you don't have to actually wait in the line while you are waiting. You can use the restroom, get a snack, or even enjoy another ride!
Feel free to comment with any questions and I will respond as soon as possible.