Avoid the use of double negatives

Two negatives should not be used in the same sentence because they destroy each other.

We should say:

I couldn’t find the keys anywhere. OR I could find the keys nowhere. (NOT I couldn’t find the keys nowhere.)
He hasn’t got any friends. OR He has got no friends. (NOT He hasn’t got no friends.)
I couldn’t find anything impressive about that painting. OR I could find nothing impressive about that painting. (NOT I couldn’t find nothing impressive about that painting.)

Ever and never

Ever is sometimes misused for never.

I have never been to the US. (NOT I have ever been to the US.)
I am never late for office. (NOT I am ever late for office.)

Note that the expressions ‘seldom or never’ and ‘seldom if ever’ are both correct.

These goods are made for export and are seldom or never sold in the country. OR These goods are made for export and are seldom if ever sold in the country. (BUT NOT These goods are made for export and are seldom or ever sold in the country.)

Else

The adverb else should be followed by but.

It is nothing else but pride.

Never and not

The use of never for not is incorrect.

Kipling was not born in London. (NOT Kipling was never born in London.)
I met him yesterday but he did not refer to the matter. (NOT I met him yesterday but he never referred to the matter.)
I do not remember ever having met him. (NOT I never remember having met him.)

So and very

So as an adverb of degree must not be used without a correlative.

Compare:
I am very weak. (NOT I am so weak.)
She is very beautiful. (NOT She is so beautiful.)
I am so weak that I cannot work.
She was so beautiful that he wanted to marry her.