I did exactly what you are doing -- UPakWeShip, port (or in my case warehouse) to door, self packing. I had a really, really good experience of my end result, (although the packing process and accompanying decisions were a nightmare lol!) so I hope I can help with some of this.
Can't help with furniture per se, at least not large pieces as I only took small stuff that could fit into a box or have a box created around it, but I did pack lots of boxes of smaller belongings, plus some irregular shaped packages.
For small but collectively heavy items (which are best in smaller boxes) I went to Office Depot and got those little squarish boxes meant to store hanging file folders.
They come in a flat pack of ten and are assembled by pulling the parts together into extremely sturdy little structures.
They do have lids and handle-holes, but I just parcel-taped the lids sealed in all directions once packed, and the handle-holes actually came in very useful for everyone who had to move the boxes and carry them, including me.
Most of my boxes were these, then a few were larger "proper" shipping boxes, again from Office Depot, the kind you have to tape together, but these proved very reliable also.
All of these stood up against the journey with flying colors -- not one was crushed or the items inside damaged.
I got creative with a bass guitar I didn't have a case for -- I padded it and taped it to one of the few pieces of what could be called furniture, which was a light, tall, folding shelving unit that happened to be the same height as the guitar. Then I improvised a self-made cardboard box around it, and taped the whole thing to death. Amazingly it all held up in the journey, nothing broken. They do advice it's best if all your "boxes are a regular and uniform size and shape, but when palletizing my stuff, the warehouse guys for UPAk were fine with the few pieces that were not quite the same as the regular boxes.
I did bubble wrap all my ornaments and other breakables, and yes, none were broken, with the one exception of the glass in just one of the several picture frames I packed (remove all your pictures though, and pack them separately or in bring them with you in your luggage rather than putting them in the shipment).
The one picture-frame glass broke because I hadn't taped it across as well as the other frame glasses which were fine.
Aside from that one breakage, everything else was intact.
General guidelines are just common sense things such as not putting heavy solid things in with breakables, packing fewer heavy items in smaller boxes and many lighter things in bigger ones (this just helps all those who have to lift these puppies), and bubble wrapping breakables very well.
Also, when filling a box with your wrapped items, don't leave any jiggle room. From what I gather, it's when things can jump around within the box that they can get broken, even if individually bubblewrapped. Pack your box tightly so that everything is one solid mass.
I got that tip from the seller's forum boards of e-Bay -- those folks pack breakables to ship to buyers every day, so they know their stuff!
I must have done something right because the whole shipment was intact but for that one piece of picture glass, and it can be replaced.
Hope this helps.
EDIT:
I woke up thinking about this and wanted to add that I forgot to mention --- as you pack, make a list.
UPak only require a list of general contents of each box -- this is for them and also for the port authorities (you fax or e-mail your list to UPak and they in turn pass that on to the receiving port I think is what happens).
But you might also want to make a more detailed list for yourself, just to know exactly what is in which box, and to check everything when you get your shipment.
Also, finally, number your boxes when you have completed all of them -- example, I wound up with 28 pieces and so marked each box "1 of 28," "2 of 28" etc. Easy to forget this last minute detail. I also wrote my name and contact number on each box.
