@ irah, glamour or illusion spells will make you appear different to others, but it won't change your appearance in any way. depending on what it is you want changed, you can cast a a spell to help achieve your goal, but it will come down to you. if you want to cast a spell to help you bulk up, slim down, have healthy hair, clean skin, you can cast a spell to help you, but you'll still have to put in the hard work. for weight spells, you'll need to work out, and with skin/hair care, you'll need to get into a daily routine. nothing with magic is instant, you need to put in some effort for it to work.
@ SolaMoon it is not possible to become any of these creatures. the reason why is the same reason why a spell can't change your appearance, magic is not all powerful, it has limitations. it's a force of nature, while powerful, it cannot go against nature. you were born human, no spell will ever change that. of course you can look into astral projection, these creatures are astral beings and many do work with them to aid their spellcraft in the same way you'd call upon a god/ess but change into one, no.