I'm writing this blog because of a block that I had recently with spell writing, so bear with me if I ramble or something. I'm kind of sick today, but I'll try to keep this as "to the point" as possible.
You get this idea for a great spell. As an example, let's say that it's a spell to help with financial trouble, like bringing money into your life. But, the moon is waning when you want to do the spell. Well, you could wait until the moon was new again, or waxing, or you could rework the spell to suit the current moon phase.
In this scenario, instead of working to bring money into your life, you should rework the spell to decrease your debt or financial burdens.
Any spell can be worked during any phase of the moon, you just have to figure out how to make it work with the phase. Right now, I'm working on a spell to cut ties with someone who nearly destroyed my life. I came up with a perfect spell, but I won't be able to work it (as is) for nearly a month, so I'm trying to rework it now for the waxing moon that's coming up soon (it was written for the waning phase, and certain details won't work for this month). You just have to look at it from every perspective and figure out other ways to accomplish your intentions.