Although wish is generally associated with hope, it is actually used mainly for regrets. For example:
- I wish I had a better job. (I don't have the job I want now)
- I wish my kids could have a better education.

Wish is used with unreal situations, so like all unreal situations in English the sentence goes one tense back in time.
If the sentence is about the present then, we use wish with the Past Pimple. For example:
- I want more time now => I wish I had more time.
- It's too hot now => I wish it wasn't so hot.

And if the sentence is about the past, we use wish with the Past Perfect. For example:
- I wanted more time => I wish I had had more time.
- It's too hot now => I wish it hadn't been so hot.

Wish ... would is used to complain about a present situation. For example:
- I wish he would speak louder..
- Don't you wish countries could stop fighting?
- I wish it would stop raining.

Wish .. would is used only for actions, not states or situations. For example:
- I wish I would be at home. - Incirrect.
- I wish I was at home / I wish I were at home. - OK

The subjunctive is a little used mood now found mainly in a few stock English phrases. Simply put it means that with if and wish, you can use were with I/he/she/it. It's particularly common with the pronoun "I", for example:
- I wish I was a rich man. OK
- I wish I were a rich man. OK
- If I was a rich man... OK
- If I were a rich man... OK

As with most older English, this is found mainly in British English.

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