[header] How to prepare for a phd as an undergraduate [title] Talk to your professors. [step] It's a good idea to talk to professors about your interests, especially professors in your field of interest. Not only have they been through the process of obtaining a phd, but they know other professors and institutions in the field. 
They'll have inside tips to prepare you for the workload, and may even be able to write a letter of recommendation for you. [substeps] Don't approach any professor at random.