Spaces between control structures and parens.

i.e, if(x) { /* blah */ } vs. if (x) { /* blah /* }. I never understood why anyone would use the second style, it's not like it makes the code substantially easier to read (in fact, I think it's aesthetically worse and more distracting), and it wastes line capacity.

I don't put spaces between the keyword or function name and the opening parenthesis, since the keyword or function name is associated with its parameters/expression; seeing a floating (...) with whitespace around it makes it look like the expression is standalone. Spaces between parameters are used when they look similar or there are decimal points/other things that could be mistaken as a comma.

Similarly, I prefer x*4 + 3*x vs x*4+3*x or x * 4 + 3 * x since it shows the operator precedence more clearly. (x * 4+3 * x would be the worse of the choices).