If you're doing anything that's growing, you do it on a waxing Moon. So that's things like expanding and empowering parts of the soul, or doing a working to gain money or gain assets or anything like that. Where you get something at the end or are more expanded in the soul afterwards.
A waning Moon is for anything that is reducing or to be removed, destroyed even. It's good for black magick, but more importantly also for spiritual workings involving removal like deep aura cleansing (you can start such a program on a waning moon, it will be much better) and also removing things like entities and unwanted people attached to you psychically. If you are undergoing a lawsuit or something like that, the waning Moon is to do with ending things, so you would do a working to curb those negative things ideally when the Moon is waning and it should aid the working quite a lot.
You can do a NinRick or like how I used to be and think from meditation you are greater than the planets or even the Gods. I know what NinRick means, but the facts remain: It doesn't work that way if you want real results in an important situation. The Moon is the closest influence in Astrology and it represents and rules the Mind itself which is your cognitive process as you are experiencing life and understanding this right now. It influences the works you do with your mind in a very deep way which if you have insights into the Moon and learn how it works over, you can master most types of workings.
I think in terms of the waxing and waning Moon, the North and South node of the Moon or Rahu and Ketu, can also be important for workings. Planets aspecting over those nodes in the current transits could have an additional effect on workings. Rahu or the North node is the waxing type node and Ketu is the waning type of node.
The Sun for example, in Scorpio or Leo conjunct Ketu while the Moon is waning could be probably the best time in a while to do removal workings for the soul and especially black magic (The Sun represents life and Ketu is endings). If such a motion is possible and common enough, that could be something to bear in mind. The Sun in Leo or Aries conjunct Rahu with a waxing Moon would be a brilliant time for stuff involving children or life, creation. Anything like that. Also probably gaining power too, but you would also bare attention to Pluto as well.
The most important planet to bare your mind to in a working sense is the Moon. It's like the Chart ruler of a working. The other ones following after it in importance are Mars, Venus and Saturn in no particular order. The Sun is important depending on the goal, but not as much for the process and circumstances surrounding the working. The Moon is the chief and ruler of all psychic workings.