Name the feeling before you try to fix it. "You are so disappointed right now" does more in the first thirty seconds of a meltdown than any solution you could offer. Ormrod's work on emotional learning is consistent: children regulate faster when they feel understood, not managed.
Stay regulated yourself. This is the hardest one and the most important. Your nervous system is doing something to their nervous system in every charged moment. A calm, low voice and a steady presence isn't just kind, it is neurologically regulatory. You are the co-regulator until they can do it themselves. Try to remain calm.
Build predictability into the day. Routines are not about rigidity, they create safety. A child who knows what comes next doesn't have to spend energy bracing for the unknown. Transition warnings, like "five more minutes, then we'll clean up" and advance notice of changes all reduce the anxiety that big feelings feed on.
Practice when everything is fine. Talk about emotions at the dinner table, during a walk, while reading a book. Name your own feelings out loud. Play games that involve losing and process it together. The time to build regulation skills is not in the middle of a meltdown.It happens in all the ordinary moments before one.
Let them lose. At games, at arguments, at getting their way. Not cruelly, consistently. A child who has never lost at Candy Land will not have the tools to lose gracefully at something that matters. Tolerance for disappointment is built in small, safe doses over a long period of time. Rescuing them every day does not help self-regulation.
Repair the pattern out loud if it needs repairing. If you recognize yourself in any of the earlier sections, if the home was loud, or unpredictable, or feelings were shut down rather than held you can say so, in age-appropriate terms. "I'm learning how to help you with big feelings, and I'm going to keep practicing" is one of the most powerful things a parent can offer. It models the exact skill you're trying to build.