Assuming that the information about you practicing Reiki is correct, I would say spell casting and the rest should be relatively easy for you as magick involves the manipulation of energy.
Simply put casting a spell (in my opinion as other people have other definitions of what a spell is) is when you use words and energy to cause a change in the world. You can use any other tools you would like to cause the change, such as herbs, stones, tarot cards, etc., as a booster to your spell.
As for divination there are many ways to divine things, tarot cards, oracle cards, scrying with a crystal ball, pendulum, water, black mirror, etc.. All you really need to do for that is look into the different kinds of divination and find the one that works best with you, the one that resonates with you.
Healing wise there are many different things you can do (as you have seen through both herbal and reiki healing). Other forms of healing can include spells cast that are supposed to help out healing in one way or another (in various ways such as spiritual, emotional, physical, mental), sending out "prayers" for healing to occur, invoking a god/dess, demon, angel, or other entity for healing, etc.
Now as for divine magick I am not really sure what you mean by that, however I will assume it is working with deities. If that is true then it could be anything from praying to a deity for assistance, invoking them for assistance, summoning them (not a wise choice exactly as many entities don't particularly like being summoned), etc.
I know that this doesn't cover everything in each subject you listed, however I hope I have helped you in some way.