If you work with the source code make sure to keep the style consistent.
Use spaces, loops should look like this: for (int i = 0; i < 42; i++), not: for(int i=0;i<42;i++).
The same goes for variables: int i = 42; not: int i=42;
Declaration of multiple variables in one line is fine, but only where it makes sense.
Example: int x, y, width, height;
Braces should look like this:
public void test() {
}
That's pretty much it. Than you for contributing!