Hello Cybersbe and Welcome!
Motivation - In brief, people are motivated in different ways. And you will need to discover what is it that motivates you. Ask yourself what was it that made you write here and ask for motivation in the first place, and that should be a pointer to get you started.
Philosophy aside, you are probably facing a form of “blank page” syndrome, which every writer experiences. If this is NOT what troubles you, then that means you have a story in mind already.
STORY IS THE KEY: The fundamental point to get motivation on any level, I believe, is knowing what story you want to tell … and knowing it well! Once you think you know your story, ask yourself what would a player want to know about it? What parts of the story do you know that other players do not … and how are you going to reveal that story to them? Who are the players going to meet? etc. etc.
I would support what other builders may have already said, and suggest writing that story to PAPER FIRST and then putting together some kind of story board. Once you have the main plot of the story in mind, then you can begin to build with the toolset … which will be quite an affair!
Also, if you are struggling with some story elements, try playing somebody else’s module to get a feel for what you like about their module, or what you would try to improve upon.
OTHER ELEMENTS: Once you have the story in mind, all other aspects of the module itself I would call “fluff” and different “fluff” appeals to different players. The strength and pace of the story is what drives players through a module whether they like the rest of the fluff or not. E.g. My wife enjoys messing around with the look of her PCs (hair, build, etc.) I get bored of that stuff just writing that sentence about it!
FINAL WARNING: You need to be dedicated to your story. If you have any thoughts of times you may not want to give it some time, then you will likely lose focus and eventually it will fail to be delivered. Now, that may not be a waste of time, as you will (hopefully) still have enjoyed the experience and learned something from it. However. just be prepared for a long haul to deliver something more special.
Of course, if it’s just a simple straight forward project you have in mind, then go for it. And as people on this thread have already said, take it in small stages … one step at a time and get help from the forums here.
READING: Apart from all the excellent advise already given with other reading in these posts, I will also give you a link to my own blog, which is currently running episodes of my second module build for NWN2. While not NWN1, it does give you an emotional connection with another builder going through their own processes of trying to breath life into a module: Episode 1 Link. (Definitely worth a read for you to start with.) These posts also describe some of my personal issues will the toolset and design process.
Extract from that blog post:
1) PLOT: Thankfully, the hard part, the plot, is already taken care of … but only in part! The point being, if I did not have a story to tell, then no matter how many area designs I have available to me, a lack of conversations or plot would quickly bring this latest project to an end. However, there is still the problem that even though I have the plot in mind, the same problems of forming a good-flowing, fully cohesive story that a player can have pleasure interacting with, remain. i.e. There are critical plot points, but I need to fill the blanks with enjoyable and meaningful content. I will need to put flesh on the bones of the plot - and that will take time to create. This also means writing all those conversations!
Other episodes available at the blog: Althéa Blog. Or click on NEWER POST at the bottom of the first link given above.
All the best with your project!