I’ve had horrible trouble with this issue and am glad to see that others seem to have found ways to grapple with it– heartening. For me, I have to change up what techniques I employ, depending on how blocked I feel (most often it is an anxiety issue causing the blockage). If it’s not too bad, I’ll listen to music that I know well and make lists of steps/thoughts. If the blockage is really bad, I need to have white noise instead of music (I like pink and brown together from YouTube). I find the binaural beats unsettling. The lists also change if I’m really anxious. When I’m facing a normal amount of stress, I just follow a detailed list and try to work through it, but if I’m REALLY freaked out (or if it’s not linear like writing a paper often is), the larger list itself becomes distracting– my brain bounces around from item to item, increasing the feeling of being overwhelmed. When that happens, I set aside the list and take a very small notebook and rewrite either next (tiny) steps or top five items/priorities/thoughts/tidbits. Sometimes this takes two or three tries and I run through a bunch of these small pages– maybe with one thought on each page even (like index cards would be). Normally this is enough to get me started. The physical paper is essential for me, because my laptop is its own distraction. It is NOT efficient (and maybe sounds a little wacko), but for me the combination of sound and using paper often works.
Good luck and let us know how it goes!