If I recall correctly, David Allen says that most people prefer to build from the ground up, but that some prefer to go the other way. And he is probably right. Personally I think I have approached it from both ends simultaneously:
It is relatively easy to do the 50 k thinking separately. You have probably done it most of your life already, and although you may never be quite satisfied with it you are gradually creating a clearer and clearer picture of what is important overall in your life (values, principles etc.). And that's it, really.
It is also relatively easy to start with tasks and projects (0 k and 10 k). You have probably dealt with those or similar concepts for ages, too.
But you have not tied the lower horizons to the higher ones yet, and I am not sure you can. The 50 k values etc tend to permeate virtually everything you do at the lower levels. You typically do not create special tasks or projects or anything to accomplish them, but they affect everything you do, like an invisible checklist in the back of your head for how you go about doing things in your day-to-day life. There is little or nothing to write or connect or "tag" on your lists. I do not see this is not a problem.
Then you have areas of responsibility (20 k). I think we are all intuitively familiar with putting headings on projects and stuff, but the "roles" interpretation of the AoR is the one I prefer. And then you have whole groups of such areas of responsibility, such as Private or Work. The groups of AoRs are described in GTD but have not been defined in terms of a level, so let's say they are 30 k (obviously above 20k). These lend themselves very well to a purely hierarchical relationship all the way down to projects and tasks "within", if you find that to be a meaningful thing to keep track of on a daily basis - I do, but I believe I am in the minority.
At 30 k you also have concrete goals and objectives of such duration or magnitude that they might affect your AoR definitions - potentially life-changing efforts in some concrete sense. These can be seen as a kind of hierarchical "super-projects" for projects and tasks - that's how I deal with them, just like groups of AoRs.
That leaves 40 k, probably the most difficult level. Truth be told, I do not have anything to say about these. Obviously, some objectives can be even larger and longer-term than others, but then it is just another level of hierarchy (an extra big 30 k or a super-30k). The more interesting aspect is that If I would like to connect my 50 k values etc to the lower levels, it would seem to have to take place at the 40 k level, because it does not happen anywhere else. But I honestly do not see a need to make that formal "matrix" connection. I am quite happy to keep them independent, the 50 k values permeating everything else in a perfectly undocumented and intuitive way, every single day, like a personal religion that is constantly evolving.