for me, being basically lazy and inclined to find something to do it FOR me, the 'easy' way to deal with the seldom-used character codes is to either:

A) look it up in a program like Map of Chars where all the possible characters are listed, and you just look up the one(s) you want. This will show you the characters available in ALL fonts on your machine..(Windows machine!)

or

B)if you do a LOT of this, to have a program like AllChars do it for you with an 'almost' intuitive use of keyboard macros. ¢ ß å é œ etc.... to make a ¢ sign, I just hit the 'ctrl' key, and then the '/' and the 'c' key in succession...the program says "oh, he wants the symbol using both those together!" ...and if you don't want to memorize them all, it has help screens with the characters grouped by type...neat!

I use both programs---I have AllChars in my startup menu so it is always there and I can ß and ë anytime I want!