Pronunciation of Lithuanian consonants

Hello my Korean friends, for my theses I need your answers about the pronunciation of Lithuanian consonants.Thank you very much.

In your opinion, why it is hard to pronounce these consonants?
There are not in Korean Language I think, and Lithuanians often misunderstand me when I pronounce the word with those sounds
For me it was the hardest to learn how to pronounce consonants v and j. J is confusing. I thought that it will have similar sound as in English language but it different. it take time for me to learn
There is no similar sound to English
those sounds do not exist in my language
We don’t have these letters in Korean and it becomes really easy to pronounce them. I was also having a hard time with the letters č or š, because it was the first time for me to see these letters somewhere.
because there are no similar sounds in Korean language, therefore, it is not easy to pronounce them