I wish and if only
There are three distinct types of I wish / if only sentences:
1 Regrets with the PAST PERFECT (the third conditional)
I wish I hadn’t got so angry.
2 Wanting change for the present or future with the PAST SIMPLE
I wish I had enough money to go to Mozambique this
3 Complaints with WOULD +INFINITIVE
I wish you wouldn’t arrive so late all the time.
You can find some quick exercises here: http://perso.wanadoo.es/autoenglish/gr.wish.p.htm