When you compare a variable (a lvalue) to a constant (not a lvalue), always write the lvalue on the right hand side of the comparison.
if ( n == 5 )
if ( 5 == n )
This will help with your debugging in case of a typo: if you mistype '==' as '=', in the first case, your code will compile just fine, resulting in a program with some hard to catch error which might take you hours to find.
In the second case however your compiler will immediately complain, since the syntax is incorrect and you will find and fix the error within seconds.
(C) notice: Thanks to Ralf Babel for this invaluable tip he published in his book, "Das Amiga Guru Buch" (originally available in german only, but to my knowledge there is a much newer english version as well)