Here are some tips to write obfuscated code:

Short and meaningless identifiers:
Because a=aaa*aa; will always be more obfuscated than result = value * factor; In order to have short identifiers, obfuscators tend to even #define many things.
Reversed array indexing:
You just have to remember that var[3] and 3[var] are equivalent.
Digraphs and trigraphs:
if(a< <:b+aa??))?? should be less readable than: if (a < (b+aa)) { f(); }
Look-alike characters:
Sometimes, it's hard to tell appart l, 1 and I or o, 0 and O. For example, if you write 10l, I bet everyone will read 101 instead.
Coding style guidelines:
Generally speaking, just try to find good coding guidelines and to try to violate them all. Those documents that you could find anywhere on the web could help you more than most things and would allow you not to buy anything.

Being Creative while designing your code is more important.

The following are the websites that guides and help you to write obfuscated code successfully.

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