English Pronunciation

1) I was learning to English pronunciation pronounce English yesterday.2) I was learning to English pronunciation English pronunciation yesterday.

1) "to" should be used with a verb ("pronounce")
2) "English pronunciation" is correct, but "to" should not be there.

I think that maybe, many Japanese people also think the same (thing / about it).

This example is more likely what I would say. It was a little difficult to correct without changing it completely.

I memorized the pronunciation of "L or R" and "EL."

"Memorized" probably isn't the best word for this sentence, but it's also not wrong.

1) I still have to do a lot of practice practicing.2) I still have a lot to practice.

I added "still" because you will continue to 'practice', but it's optional.
1) You must have a verb between "to" and "a" and if you use "do," "practice" becomes "practicing" because it is no longer a verb.
2) If you want to use practice as a verb.

I'll try to write to practice practicing with this picture.

Your grammar was almost correct here. However, I would say this sentence as:
I'll practicing writing using this picture.

The man who is reading a newspaper is wearing a suit.

This is not incorrect, but I would say it like this:
The man wearing a suit is reading a newspaper.

I don't know what he reads is reading.

It's like saying 読んでいます instead of 読みます。