Proverbs: some explanations

It's an ill wind that blows nobody any good
Rather an ambiguous saying: it does not mean simply that something has happened that is bad for everybody. It means that even if something bad for most people happens, there will almost always be someone who profits from the situation.

Great minds think alike
Used by two people who find they have like opinions, basically to flatter themselves.

Don't put all your eggs in one basket
Spread the risk around. One should not risk everything one has in a single venture.

Birds of a feather flock together
People of the same sort of character, belief or class tend to group together.

It never rains but it pours.
If something bad happens, it often seems that other bad things follow even though there is noobvious connection.

All that glitters is not gold
Do not be deceived by things or offers that appear to be attractive. They may not be what they seem!
(Actually the original saying is "All that glisters is not gold" but the word "glisters" is hardly ever heard or seen these days.)