Spiritual mean's are never enough. You could do 100 square's but if you never practice you won't improve much. It just becomes energy that is unable to burst from the soil of your underlying potential. Magick doesn't automatically solve all your problem's. You have to do the doing.
I would like to help you, but I would be lying to you if I told you that certain things can be learned very well simply with spells and by self-taught.
I can literally do 20 squares of Mars to be good at Muay Boran (my martial art) and read all of my Grand Master's books, without exception, study his DVDs and videos completely, etc.
But without my Grand Master who trains me, corrects me and explains me, I would be nothing of what I am today.
This doesn't mean that it's impossible to improve in singing on your own, you can actually study something by yourself to understand the really basic things a little.
But for certain physical things in my opinion it is difficult to self-taught with spells and that's it.
BUT IT'S *MY* OPINION.
I don't think it applies to everyone, but it definitely speed's thing's up if you have a good teacher. Most teacher's have only held me back, but if you find an exceptional one it's a gift better than any other. The God's themselves can also act in this role to an extent, if one is open enough, but it's not really the same thing as having a direct teacher to learn from and provide active/immediate feedback.
Other than that it depend's on the OP and their natural abilities. This is something that take's years/decades of practice and obsession IMO. Learning about something you're obsessed with is very different to a passing hobby. A large portion of your nervous system become's engaged and "sensitive" to all potential stimuli related to the subject in your daily experience, subconcious, and overall environment.
For example, you would be training your voice even in your regular speech. Paying attention to how birds/animals use their voices. Scrutinising every sound in your environment and how it make's you feel (don't overdo this), freeflow practicing of just messing around with your voice, etc. - anything to optimise your own ability. Your whole nervous system at least for a period of time should become oriented to this.
At some point, when you've mastered something, you are no longer just a regular human being but a sort of "subspecies" because your brain structure has changed so drastically. I don't mean this literally, but it's akin to this. For example, someone like Michael Jordan is not just a human being, but a "basketball player" - and that role itself can be considered like a subspecies. He's developed a unique brain structure, like a tool moulded to perform a specific task, and has gone beyond this broader category into a more niche one. There are better examples of course, such as Tesla or something.
What I would recommend to OP, is find a song you really love, and mimic it to perfection until you can do a cover of the song almost perfectly. From this point on, you will intuitively be able to reverse engineer the process and discover a lot about how to control your voice and all the nuances that goes into it. It need's to (or at least, should) become an obsession of your's. Then do this to other song's. Try to find a online teacher (even if it's just an online course), but don't let them drown out your own feeling/style. Read book's on music, biographies on famous musicians etc.