Waking up naturally, rather than with the jolt of an alarm clock, sometimes helps. A busy mind, thinking about getting out of bed and what you will do next can send the memory of the dream out of reach. So if you can, lay still when you awaken. Be still and don't start thinking. Sometimes drifting back off a bit brings the dream back and it's there when you awaken again.

If you remember even a bit, write that down to remember that and sometimes more will come to you later.

Some practice thinking to themselves at bedtime "I welcome all my dreams and I want to recall them when I awaken".