Just pick a brand and stick to their feeding guide,as you grow more and more you'll learn what the plant needs and when and what each nute does. But generally speaking most nutrient lines have a grow and a bloom, sometimes a micro or root for seedlings, they're are optional additives too which can improve yield, size, smell or flavour etc. Or can be quite daunting. Stick with known brands like foxfarms, biovizz, advanced nutes, flora etc. Look at the top 10 on this website. Follow their guide! 👍🌱