Minimize the use of Goto statements, especially where they can be replaced by short'ish if blocks, but don't create convoluted code just to avoid using them. Don't be afraid to use a Goto where it makes sense. Also consider making a long conditional section a separate subprogram. End conventional do loops with distinct Continue statements. I.e., don't end nested loops with the same Continue statement.
Comments Use comments liberally to describe what's being done.
Where code may be confusing, use longer comments to describe why something's being done the way that it is. Start the text of comments at the same indentation level as the code being described. Use a standard header section at the beginning of each subprogram defining its purpose. Where appropriate, align them vertically with nearby in-line comments. Define each common block variable using an in-line comment on its type statement in the include file.