Observe thousands of animals to understand the formation of animalistic life. Observe thousands of plants to understand the formation of plant life. Observe thousands of minerals to understand the formation of mineral form.
Make sure to test all things you eat or use with small amounts to make sure it's not toxic.
Toxic things wont kill or damage you if taken in small amounts.(Postnote - Not legal or medical advice)
Buy herbs cheap in bulk. Powders are the easiest to work with. Try to buy them in 250grams to 1kg.
Make sure to store everything properly so that air, bugs, animals and humidity does not ruin your ingredients and cosmetics.
Alchemical wisdom comes through experimentation. Reading is not enough and will not allow you to properly understand this art.
Alchemical work is best started early as it can run for an entire day or more sometimes.
Start with herbal recipes and experiments first.
Use more ingredients and bigger equipment to get more end products.
Be gentle with glassware.
Goodluck.