Recommended Read: Arabic Typography
Calligraphy must be studied through a qualified teacher and practiced to a high level before attempting to execute full works. It is also recommended that the student studies the traditional scripts before embarking on developing new ones. What is even more important is the need for a strong understanding of Arabic typography structure, style and uniformity.
A good starting point is a researching on Arabic typography and a good book I can recommend is by Huda Smitshuijzen Abi Fares, entitled:
A Comprehensive Sourcebook
by Huda Smitshuijzen AbiFares
This is a comprehensive study, and practical reference, of Arabic letterforms and styles beginning with a concise historical overview of the development of Arabic typography through to modern designs and technological advancements. Going beyond the historical facts, this book discusses modern design issues - pertaining to the creation of letterforms and to modern Arabic typographic design - as a communication tool marrying functionality to aesthetic delight.
by Saqi Books