I have made a One Block Wonder. I think the thing that is wrong with the pattern is they tell you to use the width of the fabric and it makes it really hard to line up the repeats of the fabric. When I make a Wackeroo Quilt (stack and Whack) they had us cut the fabric on the fold first and then line up using the 22 inches of fabric. This is a lot easier than doing it the other way around. You really need a place to lay the quilt out for when you are sewing it together and you need to number your rows. Plus you need to use lots of pins when you are sewing it. I laid mine on the bed as I was working on it while we were down south in our 5th wheel.
Another thing I found out on the OBW was that your pattern should not be real dense. My black and white did not have a lot of background and it makes it really busy. I think the nices ones I have seen are the ones with more background color and less pattern. I hope you can understand what I am saying about this.
As for the bargello I made one of those as well. Again you need a place to lay the pieces out and make sure to number the rows. We lived in a bigger house that that time and I laid it down on our basement floor and I would go over and pick it up the pieces as I was sewing it together.