The best path to study botany is totally dependent on what your interests are related to that very subject. For instance, the field of applied botany requires a student to form a good level of concepts related to the different features of plants. This can be done simply by observing various plants that are grown near your area. Apart from that, botany students can also study various different books that tell plant characteristics.
Honestly, personal study is the best way to gather knowledge about any subject that you want to. Moreover, The internet is a great resource to study online for free.