Your blocks are terrific looking!
The best advice I would give anyone of any level of experience is to pay attention to making sure your seams are straight and even. Whatever size your seam allowance is if your seams are at all crooked it will show in the finished size of your blocks. Also pay close attention to making sure your seams meet accurately and things will fall in place like they should!!
I like to take the time to tack a stitch instead of using pins when I am joining blocks together. A stitch is less likely to allow the fabric to move and pins don't always keep the fabric in place well enough when you are matching seams. I tack everywhere 2 seams meet and at the ends where the seam will go through. If you place your tacks where the seam will go through you don't have to take them back out and you don't have to mess with pins.
Keep up the good work!! Your blocks are looking great!!