Hi,
As someone relatively new to OF and GTD and dealing with a lot of large/complex projects both at work and in my other "serious" activities, I agree with both of the previous posts and would mention a few things that were not obvious to me but help greatly to reduce the "overwhelming" factor.
As soon as I think of something, I found that it was a good practice to use the inbox concept to capture the idea:
- the inbox allows a kind of mini review at the end of the day about the new ideas you had, and is liberating for me in a way similar to the "bigger" project review (as opposed to filing the task right away in one of the sub-projects, which I still do for tasks that are no-brainer or don't make me "anxious");
- I sometime have to "push" myself to do it immediately but it is very liberating as well;
- if the project is long enough, and you do that systematically along with reasonably regular project review, I reach a point after a few weeks or months where I "studied" the project without realizing it, and now it "lives" in my mind (I hope the image makes sense, I'm not a native English speaker) and it's less overwhelming;
- related to the previous point, I also gain confidence that I didn't miss something important or I would have realized it by now, and if something new comes up, I can figure out quickly and confidently what to do about that.
(And I stress again the importance of taking the time to do the project review regularly, every 1-2 weeks I would say is a good pace if there's no short deadlines.)
Using a hierarchy that is as flat as possible in terms of folders and action groups. I also find for now that my projects should "fit on one screen" to be comfortable, because I can see everything at once for that section. But generally, less than 4-5 actions is too small and usually leads to be overwhelmed, and above 15-20 starts to get hard to consider/order/etc. as a single piece (I sometimes use action groups to deal with that). In other words, trying to make it logicial and easy to prioritize "between" projects (project A is more important than project B, or one is needed for the other to start) and within each project (in this project, the sequence of events is...). In relation to that also taking the time to identify the right sequence in which to perform the actions, is something that helps but that I am still struggling with in many cases. Again standard GTD but being new at it, it's something that is useful to learn and integrate.
Physical material: I realized that for certain types of tasks and thinking, it works better when I map it out physically as mentioned by a previous poster. One thing that helps me is a board where I can pin pieces of paper, so this way I can group things together and so on, and easily clean up the clutter after; all the while preserving the possibility to quickly restore my workspace, or move it around (go to a meeting, go work in another room, etc.). I can also let that board in a visible place so that it helps the above process of letting the project sync in until it is "known", and using it as a kind of inbox to pin related ideas to the "mind map".
Using the "hiding" features in OF: by setting start dates, dependencies, "on hold" contexts, or manually putting a project "on hold", you can know everything is there but look only at the useful tasks even in generic perspectives. (Learning to use contexts and trust the "available" filter was already a huge improvement for me. I'm hoping to work only with "next actions" eventually! :) )
Working better with contexts: it is covered in many posts, blogs, and so on, but it is important to mention it. Also, sometimes I will create a special variation of an existing context. For example., if I have to do shopping for such a project, it is not useful to use a standard "errand" context because I will probably want to check new equipment, talk with the vendor, etc. It's not like "oh, while I stop to buy milk, is there anything useful for project X I could shop for?" So I will create a sub-context especially for that under my errands context, because it can be useful to see it if I'm going out, but I will consider it differently of plan it eventually, and can include it in perspectives slightly different than the rest.
Whew, turned out to be a longer post than I thought... I hope this helps!
Julien