There are so many ways to make tea, you can spend days reading and researching this subject.
If you don't have a compost pile where the natural composting process creates compost rich in naturally occurring bacterial and fungal species you can buy bacterial and or fungal inocculants to create your own tea.
For example many products contain one or more strains of mycorrhizae (beneficial, symbiotic fungi) and or beneficial bacteria such as Bacillus thuringiensis, Bacillus licheniformis, etc.
Some of these products also contains microbial nutrients such as maltodextrin, seaweed extract and or yeast extract to feed the bacteria and fungi.
In general, I have found that using these teas with super soil reduces to eliminates any problems from pests as well as maintaining the overall health of the plant.
I use compost tea from the compost pile in the summer and I brew my own tea using PHC Biopak in the winter when the compost pile is not active.