Keep a pen & paper or journal by your bed, within easy reach.
If you can’t write out your Dreams, you can talk them into a recorder, & transcribe them later.
Keep a small notebook & pen with you at all times to jot down any Dream fragments that come to you during the day, or use a memo app on your phone.
When you wake up, if the Dream’s right there, record it immediately.
If the Dream’s not there, don’t move, or only move enough to keep from falling back asleep, & wait. Allow the Dream to return to you. Don’t think about remembering it – it will wake you up to daily consciousness too much – just be receptive & welcoming to the Dream.
Jot down anything that you get: a color, a scent, a mood, a word, a person. This may trigger recall of the Dream now or later in the day. Even if it doesn’t, it gets you in the habit of recording whatever you bring with you from sleep.