This product was very easy to assemble on my own.  My advise is to lay out all the pieces first on a tarp, and most importantly, make sure all of the pieces with 'screw holes' are facing up. When I was fitting the pieces together, I found it difficult to keep the shape square, so I pushed one side of the trellis against a straight wall...and the rest was easy!  
The assembly instructions ask you to purchase a glue to attach the post caps to the vertical rails.  I used a PVC glue which worked well.  Also, to increase the stability of the trellis, I put the glue at the bottoms of all the vertical rails (parts 6-9) when inserted into the bottom cross rail (Part 4).