Decide which skills you need. Many resources exist for learning Persian. However, you will have a better chance of mastering it if you choose the skills you'd like to learn before beginning. For example, someone who wants to learn Persian for travel may only wish to study listening and speaking, while a language student who needs Persian for academic research may choose to focus on the written language. Students of the written language should be aware that Persian can be written in Perso-Arabic script, with the Cyrillic alphabet, or with a Romanized Persian alphabet, among other options. The most appropriate writing system will vary depending on the student's purposes.
Master the basics on the Internet. After familiarizing yourself with the alphabet, which has six vowels and twenty-three consonants, study basic grammar. Many online resources exist to help beginning students of Persian; websites like Easy Persian walk you through the basics of the language, as well as providing a limited amount of vocabulary.
Deepen your study with a textbook. Books like "Learning Persian/Farsi" will take the basic knowledge you've acquired on the Internet to the next level. By clarifying finer points of grammar and providing you with more vocabulary, you will prepare yourself for many aspects of more advanced study.
Listen to podcasts. For students who wish to speak and understand Persian, extensive time spent listening to the language is crucial. Podcasts such as SBS Persian-Farsi will help you become familiar with the language as it is spoken, helping you to recreate the sounds and tones of the spoken language.
Speak with a native. By posting on websites, you can find many native speakers from the Persian-American community, particularly in larger cities, who will be willing to speak with you or provide tutoring sessions for a fee. Even if this is over the telephone or by Skype, speaking with a native will help you to perfect the knowledge you have gained through the resources you have studied on your own.