I keep a word document on the task bar with all the odd symbols like
£ $ € ¢ ¼ ½ ¾ º ® © ™ ± ² ³ √ ℅ ....
in it. Use the "Insert" - "Symbol" menu to pick the ones you need a lot.
When you need a symbol, just open the file, copy your symbol and paste. Its just as quick as trying to remember all those weird key combinations.
Of course, you can always invent your own simpler "Hot Keys"...