How can you be sure of your English pronunciation?

منذ ٦ أعوام

By grouping words together that sound the same! That's how to do it.
For example: there, bear, fair, care, dare, wear, pair, spare, and keep adding same-sounding words.
Another good group is: beer, here, clear, dear, near, fear, steer, gear, hear, deer, and so on.

I find Spanish speakers have great difficulty in pronuncing these words properly because of how they learn to read: coast, most, roast, toast, boast, ghost, post.

One more is: note, boat, coat, gloat, vote, and so on.

I hope you can compile more groups of same-sounding words.