" It would also help if I could iron properly!"
I always iron each seam as soon as I sew it, before I do another seam. I always press to the dark side.
With the block that you showed above: If you'll sew all your pressed units together into a completed block, then go to the center of your block (where all your seams come together)and UNSEW almost 1/4 inch, you can then fan out or swirl your seam ends a lot flatter. (Wow- that sentence sure was a mouthful, wasn't it?) That way you won't have a big lump in the middle of your block. It'll lay a whole lot flatter that way. Someone else may know an even better way to do it. Personally, I'm always up for learning something new or an easier way to do it.