1. English is a language governed by rules. You should never deviate from these rules, except when there are deviations from the rules.
2. There are many deviations from the rules.
3.The deviations are random. There are no rules governing these deviations. For instance, the letters "ough" can be pronounced in at least 7 ways:
-Greenhough (my English teacher's name. Typical.) = off
-though - oe
-rough = uff
-bough = ow
How will you know when to use which pronunciation? You will not. As noted above, there are no rules governing these deviations.
4.Deviation from the rules is a rule of English.
5. When in doubt, insert the word cool, s%&t, F*$k or Like, and you will be fine.
6. I have not mentioned various dialects found across the world and within countries. Essentially these are languages in themselves, some have rules, others no discernable rules, and yet others made up entirely of deviations from the rules.
7. Good luck. To quote Eddie Izzard, creator of the English language (no, not really, too busy touching up his makeup): "That's the rules, that... I've just made up."