With any new language, flash cards are beneficial; it's even more beneficial when learning a visual language like sign language.
The flash cards should show a visual representation of the hand signal you should make for the word you are learning.
They are easy to transport meaning you can either keep them around the house for study or take them with you wherever you go for a quick reference tool.
Flash cards work best to supplement the education you receive from online program or taking classes.
The more tools you use to aid you in learning the better the experience will be.
Flash cards can help you practice what you've learned in any location.
As you start learning ASL, find a good book on the subject and keep it with you everywhere you go.
This way, if you have free time you can practice...
and you can refer to the book if you run into someone you can sign with.
The book can teach or remind you how to sign different words.
Of course, learning ASL from only a book would be difficult.
It's possible, but nowadays you can use many other tools as well, whether in a classroom or online.
A book, however, is a great reference tool and can help you to learn sign language more quickly.
Sign language is a completely different and new language and not just a translation from words to hands - you need to understand this going in.
When using American sign language, you'll discover that you will not convert every word that is spoken in an English sentence into a sign.
Much of the meaning with sign language is carried through eye contact and body language in addition to the hand signals.
When using a spoken language, eye contact is not essential for a conversation.
In sign language, however, looking away signals that the conversation is over, so you have to get accustomed to these differences.