I find that spells, are really just a method of "putting yourself into it."
Dance, song, etc, are other methods of putting yourself into something. Ideas, such as healing, are hard to put yourself into when you really don't know what to do.
A dance, song, spell, etc, are a catalyst to connect your intention to your idea.
In my humble opinion, magic is influence. A smile, a kiss, etc, can be magic. They can change things, heal, give hope, give comfort, etc. Someone can exercise strong magic in a smile, a word, dance, etc.
Part of what magic, as we like to think of the term, is to influence elements not exactly human. Such things might be animal communication, healing plants, healing people, influence over external events, etc. (I love this word, "etc" by the way.)
Magic is really about communication. Communicating to the trees, rocks, animals, spirit, etc, is based upon the idea that these things are actually alive and are capable of hearing and responding.
But the language we use. . . . is mostly spirit and emotion. Thus, effectiveness is about the dept of connection.
I believe that life is written right into the laws of universe. I believe that "truth" is actually alive, and thus creates living beings when giving opportunity. And not only that, the truth tends and seeks to create opportunity for life.
Communicating with the universe is possible through deeper connection to our own elements of existence. Our feelings, (emotions) are deeper, more real, and a more true form of ourselves. Herein lies effective magic. Our emotions (energy in motion) give shape and form to our existence. Our emotions define and predict our behavior. Our emotions are like electrical/chemical elements that the universe responds and reacts to.
So in a very really way, we don't actually change the universe, but rather, we change how the universe reacts to us. The universe is a set of rules and laws that we cannot change. However, it reacts to us, just like gasoline reacts to a flame. How it reacts to us. . . . there in lies the magic.
Depending upon what we are. . . . the universe reacts to us. So the change that we seek to make, or the influence we want to apply. . . is to ourselves.
We attract or repel things based upon our own energetic configuration. Radio Frequency is a good analogy of this. Two different channels, playing completely different messages can exist in the same space completely oblivious of each other. Depending upon what we are tuned into, we both influence others things in the realm and are influenced by things in that realm.
A fearful, hateful state of mind will cause the universe to react in a specific way.
We cannot really change things as much as change ourselves. Faith and belief are a fundamental power, but are elements that "we have and are."
Effective magic is more about expression of self. When we doubt ourselves, the universe reacts accordingly. So effectiveness is about, "getting in touch with your deeper reality." Your emotions. Not surface or simulated emotions, but the deeper stuff. . . . . most of which we fear and seek to hide.