bachslunch

Buying online tickets for most attractions in my experience has been straightforward. Disneyland (perhaps not surprisingly) is different. Some advice based on what I did:

--When purchasing at the Disneyland website, be sure to enter your credit card information exactly as it appears on your statements. If that happens to be (for example):

Donald W Duck
unitt No.8888
777 Happiest Pl.
Anaheim CA 99999

be sure to enter it that way. Spelling, punctuation, capitalization, spacing, and line ordering all matter. If you don't, expect their system to reject the purchase attempt until you get it exactly right. It would also be wise to check with your credit card folks to make sure any rejected purchase attempts indeed were rejected. Mine were, fortunately.

--Do not purchase tickets online at the last minute; give yourself at least two days lead time, preferably more. With most places, you will be sent a PDF almost immediately after purchase so you can print online. Not here. You will be sent instead a link to the Disneyland website, where you (eventually) get to click and print. Note that there is a delay between purchase and when the ticket is ready to print from their website, and it can take as long as 24 hours before the ticket is available. In fact, they tell you to go to the will-call window if you are purchasing online the day before you want to go -- which kind of defeats the purpose. My delay was about 6 hours, and fortunately my attempt to purchase was made several weeks ahead.

--Is it a good idea to purchase tickets online ahead of time? Given that you have to go through a security line and then an admittance line, I think so. Standing in yet another line to either purchase a ticket or do a will-call window pickup strikes me as unwise. Getting into the park as early as possible is a smart decision, at least in my experience.

marvelousmouse

You can also purchase a few different tickets at stores like Safeway, and it's less of a hassle.

Landseaair

You can also purchase tickets on the Disneyland app. I did this for a one day visit in March. I purchased a few days before the day we were going but the barcodes came right through so I probably could have done it the morning of the date we went.
I purchased 4 adult and two child tickets. Each ticket was assigned one of our party names. We just got in line for entrance to the park, and they scanned each barcode on my phone as each family member went through.
I love having the app while visiting the parks because you can see ride wait times, and where and what characters are out at any given time. Also just having a map of the parks is great.
One issue did arise though- DH was one of the people I bought a ticket for, but on the day of our planned visit he wasn't feeling well. We decided to go ahead and go as planned and had a great day. When we were leaving the parks I asked about getting a refund for the ticket I had purchased for him.
Basically you can't get a refund. I still have his ticket on my app, ready to use at any time until the end of 2018 I believe. Also, the price I paid for the ticket was for a value day, 1 park entrance. If we go on a more expensive day or want to get a park hopper ticket I will need to pay the difference. So I've got the credit, but no refunds apparently. Also it's issued in DH's name. I'm not sure if they would let me transfer that saved ticket to another name.
I'm not too concerned about using the credit, we get down there fairly often. But I would be careful about purchasing ahead of time through the app if you don't have any future plans to be in the area, in case there are any last minute changes on the day of your visit.

Kazza3013

If I arrive at Annaheim the day before my planned visit, would it be best to purchase the tickets from Disneyland then? Is it possible to go to the entrance the day before and do this?

Landseaair

If you are staying in the area, some of the hotels sell tickets to the parks on their property. Their websites will indicate if they do.
You can walk to the entrance area and buy your tickets ahead of time, and lines would certainly be shorter than they are first thing in the morning.
It would depend on whether you wanted to take the time to do that though.
In my opinion if you arrived to buy tickets about an hour before the parks open you should be fine. Disney has a way of opening up more of their ticket kiosks, more lines to get in, and more of everything inside the parks when they are having a higher census day.
Just allow yourself plenty of time when arriving- if driving just getting in the parking garages takes time, then you walk or take a shuttle, it all takes longer than imagined. Try to be at the kiosks an hour before opening time!