*** Sir Ian ninja'd my dissertation. I typed it up already, so I'm going to leave it - but I'm rehashing some of what he said ***
*** Edit: Forgot to mention a different in armors; Sir Edward has cuisses but no greaves or sabatons, whereas Sir Ian and I both have cased (closed) greaves and sabatons. Having the demi-greave strap taking some weight by tightening down above the calf may be necessary with the lack of greaves? ***
This might help some:
http://www.james-anderson-iii.com/tutorials/pages/how-a-man-shall-be-armed/Pardon the horribly inaccurate mail fauld suspension, it was properly attached to the arming coat a couple months ago, and voiders to follow. I have newer pics I need to get online at some point.
The general principle is the front points should be as short as possible and attached/pivot right near the natural inset of the upper thigh. The side points will be longer, and are primarily there to help keep the leg armor from "twisting" sideways on the upper thigh. Sometimes there are two sets of points on the side, directly at the outer edges and another in-between that and the front point.
Greaves should rest on the calf and be self-supporting - if you didn't get your greaves done from a leg casting, you're probably out of luck. I have somewhat stocky calves, and the way my calf muscles flex prevents the greaves from sitting nicely over them without pinching when flexing during motion. My fallback plan was that they ride on the top of the sabatons (and is period appropriate in appearance). It does put some weight on the sabatons themselves, but it's negligible to me until it's been 6+ hours in harness.
I have the cuisses riding on a peg/hole from the greaves. This helps keep the cuisses somewhat "preloaded" in that they aren't pulling the whole weight down off my arming coat, and gives the points a small bit of slack thanks to the articulation at the knees.
The lower cuisse strap goes around the greave. Some leg harnesses won't have this if they are a single assembly (very late period armors), or, the greaves may only have a lower strap since the strap from the demi-greave makes the upper greave strap redundant. In this case, the greave usually has a retaining pin/strap on the upper rear that the demi-greave strap passes through/over to help keep the greave closed and keep the strap in place. My new set of greaves has that retaining hole; I'll get some updated pictures since I need to replace my greave straps anyway.
The cuisse strap that goes behind the knees should not be overly tightened. It is to keep the knee from flopping forward too much when articulating, and exposing more leg than needed. If it is too tight, it can cut off circulation, and can also bind up on the fabric when really flexing your legs (like kneeling) - less of an issue if you're wearing only tights/leggings.
The upper cuisse strap around the thigh should, unless you have very pole-shaped legs, be somewhat loose as well. If it is too tight to try to support the weight, when your muscles flex as you move around, the cuisses will keep riding downwards, but can't go back up (most people's thighs are larger at the top and narrow down towards the knees). It is another strap primarily to keep the armor from flopping away loosely or over-exposing more fleshy bits - but should not be supporting weight.
Generally speaking, the straps on the cuisses shouldn't be supporting any weight. The only exception is the demi-greave strap at the bottom, if there is no pin/post on the greave to attach the two assemblies. Even then, if it's bearing any weight, it should be minimal; almost all of the weight should be carried from the arming garment.
I'd ditch the belt and point from your gambeson if possible. If not, a pourpoint is far better than a belt. Unless you do an X-harness style belt like my mail fauld thing - but again, that's historically inaccurate (or rather, I never saw any examples) and was a modern concession so that I had adjustable height of my fauld.
Let me know if you need/want any specific pictures or more info.
