It also helps to use the Japanese pronounciations and accents. Some examples:
Pokki (pronouced Poh (rhymes with "go") then a pause, then Ki (rhymes with "me") Poh Ki, is the sound of stick breaking, which is why those chocolate sticks are called "Pocky"
https://youtu.be/IQQKnwZT55o?t=76
fuwafuwa (shown in the article), is clearly a soft sound. Vs say "crack" (an english onomatopoeia sound).
"zarazara" (zah-rah-zah-rah) vs "sarasara" (sah-rah-sah-rah) note: you need to roll the R one roll and say the word fast. "zarazara" is rough like sandpaper, "sarasara" is smooth like a kitchen counter. The zzzzz vs the sssss feels pretty clear after so many years of practice. zzzzz (bees go buzzzz in English) is clearly a buzziers more vibrating sound than sssss (snakes go ssssss in English)
"putsu=putsu" (pronounced puts-puts), vs "pata-pata" vs "zaa-zaa" are different sounds for rain. The rain is falling "Zaa-Zaa" is much harder (imagine hard rain on a thin aluminum roof) than "pata-pata" light rain (just enough for it to make noise) or "puts-puts", a sprinkle.
It's more a question of whether the word's sound evokes a particular feeling or impression in the listener.
To some extent this is dependent on your spoken language and culture, but it can be surprisingly universal. See e.g. https://en.wikipedia.org/wiki/Bouba/kiki_effect
Phenomimes are onomatopoeia that depict something closer to an action than a sound - for example "powering up" (can't recall this one sorry) or "to be spinning around" (guruguru).
Doubled base onomatopoeia are not unique to Japanese either. Think of "bam-bam", "pop-pop", "click-click", "chirp-chirp", "oink-oink" or a bit less strictly "rattattat". I believe the technical linguistic term for this is called reduplication.
Following this, English has some good examples for words that aren't imitating a sound. (Wishy-washy, zig-zag, tip-top).
Most words like this are limited to the i-a, i-o axis which are also vowels in Japanese.