The best way to learn the Wiccan (Theban) alphabet, or any new alphabet, is with lots of practice. The more variety you add to your practice the faster and more thoroughly you will learn.
Make yourself a bunch of these, as small or as large as you like. When I learned how to read Kanji I had cards of varying sizes, small for travel, large for at home. If I had a moment to spare I would flip through them. You can use flashcards by yourself or with a friend.
When you make them, write one Theban character on the front and the corresponding English letter on the back. In some instances ( U and V for example) a few characters of Theban can translate into one or more English letters. Make certain you can recognize which ones and that you give both letters for an answer when flipping through your cards.
Always remember, short spurts of language learning will work best. Don't sit down with flash cards and peg through them for an hour. Use them for five minutes here and there several times a day. You'll learn them more efficiently this way.
Also, mix them up from the start. Learning letters in order will only hinder your ability to translate later. You've got to be able to recognize characters quickly to efficiently read and write a new alphabet.
There are mixed learning options for Theban just as there are to learn more common languages. Some offer computer lessons, ready-made flashcards, learning games and books written in Theban. Because all people learn in different ways it can be very rewarding to research a package such as the one offered at http://www.ytown.com/ebooks/theban.html . All-inclusive packages are very convenient in that someone has put together learning tools for you.
When learning a new language reading just above your level can jump start your brain. Keep a language key nearby and try to translate some Theban text. You'll be practicing without realizing it as you try to decipher the code.
Because Theban characters are very different than English characters you will need to practice your handwriting. If you're very serious about reproducing the beauty of this alphabet than you will need to invest in some calligraphic equipment. You can purchase an inexpensive kit at most craft stores. If you're a novice, make certain your kit comes with a book or you will be lost with just a quill tip, some ink and the pen.
One of the tricks to learning a new language is using association. This will be personal to your own learning process. Try to match the Theban characters with images that make sense to you. Associate from there. For example: The Theban letter Y is very different from the English one. You may associate it with the phrase "WHY does the letter Y look like two M's smashed together?" With some imagination you will come up with strange associations that make little sense to anyone else but you. Run with them.