Almost identical kanji

I wonder if there are any public database of most often confused kanjis. 

The first pair I had trouble memorizing difference were 持つ(to hold/carry) and 待つ(to wait)

Today I run into new pair: 猫(cat) and 描く(to draw/paint )

I was told that after memorizing 500+ it would no longer be a problem. 

But right now, I can't believe it ( but only 6 month ago I thought that I would never learn hiragana )

P.S. One more - 島( island ) and 鳥( bird )

P.P.S. And  another one - 便( mail,convenience ) and　使 ( to use )