Download the Disneyland app. And pay for Maxpass - it allows you to book your fastpasses through the app. You can still use your ticket to get paper fastpasses if you don’t get maxpass but to me it’s worth not running back and forth across the park.

With the app you can also do mobile order for food which will help staying out of lines.

Finally, make sure to get a park hopper. The two parks are so close that it’s really easy to hop between them multiple times a day.

Disneyland doesn’t require nearly the amount of planning as WDW. You don’t need to make dining reservations months in advance. Most places will probably have availability day of - but if there is something you HAVE to do then you can book 60 days ahead. You can’t pre-book fastpasses so don’t even stress about it.

Most (if not all) of fantasyland doesn’t have fastpasses at all so make sure to go there at rope drop at least one day to skip the long lines. Do Peter Pan first - it always has the longest line.