The Process of Scripting?

[Cubical]

Every time I have started working on creating a server I have always started just making systems/scripts but I never did it in any particular order so nothing really fit right. I would always get to the point where I would say to myself 'How can I incorporate this with that.' and I would just get stumped and frustrated and either start all over or just give up. Here's what my question is; What process do you use when creating a server, by this I mean what do you make first then move on to making.

Movement->
GUIs->
Item Database->
Health/Damage->
Hit Detection->
Item Creation->
ect

I would really like to know the actual process in creating a successfully running server so I don't keep making the same mistakes. I have the Ideas I just don't know what order to create them in. I'm sure this will end up helping other players as well.