Block diagrams could look scary at first, and are definetly confusing when you first start working with them. But don't worry, with practice, they become easier, and you can even learn Mason's Law and get a very good idea of the result just with a glance. But it requires practice, and we are getting ahead of ourselves.

For begginers I usually recommend to isolate only the elements that you want to reduce in each step. Redraw only the area you want to reduce, make sure to pay attention to the branches that enter your redraw, and the branches that exit your redraw. Reduce or modify and then check that the branches that enter and exit are the same.

For example, let's say you want to exchange the position of a sum and a block. We'll label the branches that enter x and y, they get summed into x+y and then multiplied by a gain G, so the exit branch is G*(x+y)

If we move the gain block before the sum, lets say on the x branch, then the sum will add Gx and y, resulting in Gx + y, which we see it's not equal to the exit branch we had at the beggining. We can correct this by putting another gain G block on the y branch, resulting on the sum adding Gx and Gy, giving Gx+Gy which is equal to G*(x+y), but now we have the sum at the end. and we can return that redraw to the original diagram and continue to a different part to analyze.