Beginners Japanese learning resources

I want to learn Japanese Language by myself.

I googled around and there are some resources but due to the fact that I have absolutely no idea what I could be missing, I was looking for some well thought out answers about what learning materials will be a good start.

I have no previous experience in Japanese. I need something that's based or feedback, has a relatively slow pace and includes exercise materials. I prefer very lengthy courses.

My native language is Bengali.