Japanese "r" is neither English "L" nor "R". -If you pronounce 『らりるれろ』with English "R", your Japanese would sound really foreign; the air is escaping from your mouth a little too much. -If you pronounce them with English front "L" as in "lip", that's too front. -If you pronounce them with rear "L" as in "apple," that's too rear. -If you happen to know Spanish or Italian and if you pronounce them with Spanish or Italian soft "R", you might be getting somewhat close, but still too trilling. -It's more like American English "t" in "better" or "letter" although I would say it's still too trilling. You can transcribe the Japanese 『らりるれろ』 with something called IPA (International Phonetic Alphabet), but probably, you don't want to know. c.f. excerpt from "The Sounds of the World's Languages" by Peter Ladefoged and Ian Maddieson↓ https://namakajiri.net/nikki/ladefoget-maddieson-on-japanese-phonetics/ So, I think the best way to master the sound is just keep paying attention to native speakers' "らりるれろ" sounds and try not to rely on the romanized characters. If you have someone to check your pronunciation, that will be even better. But in any case, it is probably a safer choice not to assume 『らりるれろ』to be "ra, ri, ru, re, ro" and just take 『らりるれろ』as 『らりるれろ』.

The Japanese R sound(ラ行 or ら行) is tricky to pronounce even for native speakers. That is completely different from the English R sound. I rather think the sound may be a little close to the English L sound. At first, open your mouth a little bit. Unlike English, don't move your mouth muscles too much. After that, move the tip of your tongue close to behind your front teeth. After that, slide your tongue a little lower just as you pronounce the English L sound, but don't move your mouth to the side.

Thought this was a post concerning English. Response removed.

Oops, I thought you were Japanese. Edited my response as well, although entering the word in Google translate and using the audio function would work also. Generally speaking though, the ら、り、る、れ、ろ is just a softer hybrid of the R/L sound.