There are many ways to use magic but we need a system of magic so that we can wrap our heads around it and save time. Not having to invent magic to help in combat or even everyday life situations can come in handy.
There are many types of magic,
Elemental Manipulation: The ability to control the elements, fire, water, earth, and air. There are also advanced forms of these basic elements that exist by changing some of their characteristics or combining them with other elements.
Advanced magic:
Lightning magic, the ability to control and conjure lightning.
Ice magic, the ability to conjure and control ice.
Crystal magic, the ability to conjure and control crystals and gemstones.
Chloro magic, the ability to conjure and control plants and vegetation.
Toxic magic, the ability to use and conjure multiple poisons.
Lava magic, the ability to control and conjure lava and magma.
Psycho magic, the ability to use mental manipulation and psychic abilities like extrasensory perception, telepathy, telekinesis, etc.
Metal magic, the ability to control and conjure any type of metal.
Vibra magic, the ability to control and create vibrations in any scale depending on the amount of magic power used.
Blood magic, the ability to control your own blood or the blood of others.
Existence magic: Holy magic, Darkness magic, Cosmo magic, and Time magic. These are extremely advanced forms of magic that come with different carrying levels of difficulty. Cosmo and Time magic is a type of magic only available to God and his direct subordinates and anyone he wishes to grant these powers to. Holy magic is the ability to heal and/or strengthen those around you, it is called holy magic because of its divine nature. Darkness magic covers any sort of magic that is associated with darkness and/or death, hence the name. Just because these two magics have opposite natures does not mean that the users are bad or good people necessarily. It is the user's choice of how the magic is used.
In conclusion, the only thing stopping you from using any type of magic is your imagination, and basic understanding of the science behind the concepts of the magic you are using. Control and amount of mana determine how well and for how long you can use your magic as well as the scale of the magic. If someone is having a heart attack, healing their whole body will only be a waste of magic power. If you do not have the necessary knowledge you will not be able to take your magic to the next level.