Just a key word or a symbol that means something to you should work fine, and this sort of magick can be streangthened by incorperating in magickal herbology, colourology, christals, and almost any other sort of magick you know how to use. It's a diverse art, and I would suggest bringing it together with one you're already good at. I, personally, use the runes from the Elder Futhark, as I'm also a divinist and they hold a lot of significance to me, or incorperate in herbology. However, if you have an area of magick that you specialise in, or a preferance, it'll be easy to mix the two.
Inscription magick is based mostly around intentions, and putting your intentions into whatever your doing, so just make sure you clear your mind and focus your energy before you start, to make sure you don't make any little mistakes. And make sure your heart's in it, that's the important part.