Best way to use functions?

I would adjust it so your Consts/Globals are before your graphics setup (and consts before globals):
1. constants
2. globals
3. graphic setup
4. main loop
call_function1 ; keyboard config
call_function2 ; map loading
call_function3 ; setup collisions
call_function4; conditions for finishing the current map
call_function5; highscore
5. functions (function1, function2, function3, etc.)

Where are Types? I would place them just after Constants.