You need to know what is on your plate and what you want to put first. First doesn't always mean you will get it finished first but it is a focus.

When working on stuff there's always something that is going to be holding up other things. This is the critical path and you need to make sure that you order your items accordingly so that you don't push off the critical path and prolong what you're working on.

When you're working on a project especially a long one it is better to take your time and do things right instead of rushing. You might miss certain details