like everyone is saying, tea is a good start and vary useful because the herbs just have the natural properties along side there magical uses
also from my time working in a tea shop ive come to describe teas caffeine as a 'softer' caffeine. where things like energy drinks or even coffee will give you a fast hard boost, tea is calmer and more subtle and natural.
a potion may not be what you need, just a good tea with a lot of good energy worked into it. i like green teas for a day to day use, but black teas have more caffeine in them if you need something stronger. other herbs can be added too if you need something else (like ginseng which is an amazing herb)
id do some research , or you can email me for some herbs for other uses if you want