If you're on a Windows-based machine, there's a handy little application called 'Character Map', usually tucked away in 'Accessories' filed under 'System Tools'. To ensure that your readers can make out the nifty symbols you use, pick a standard font like Arial or Times New Roman, and then scroll down beyond the standard alphanumerics. You can also use this to do diacritical marks like umlauts, accents, and so forth. Single-click to zoom in on a character, double-click to put it in the copy-box.
If you find you've got a favored selection, make a Notepad document and paste them in there, and save it to a convenient spot so you can just copy, paste, and go.
(I like to use this code
[sup][size=6pt]*[/size][/sup] to give my footnotes that added elevation.)