One thing that makes it easier to press seams open is a "seam stick."
They are available online:
http://www.nancysnotions.com/product...+seam+stick.do
http://www.thesewingplace.com/Seam-Stick-p/nt-ss.htm
By laying your seam atop a seam stick to press the seam open, you won't catch other nearby seams and "un-open" them.
You can make your own seam stick easily. Get a round length of wood, like a dowel, or a closet bar. The diameter should be an inch and a quarter or an inch or thereabouts. Too small and it's hard to use, too big and you will have a hard time finding a place to buy one.
http://www.instructables.com/id/Make...for-Tailoring/
It can be whatever length you want it to be. Shorter is nice for short seams, blocks, and if you keep a small pressing station at your sewing machine. Longer (like from a closet bar) is nice for long seams, like strip sets. This is especially useful on strip sets or large sections of a quilt that are already completed, where you might press one seam open and not notice that you have also caught a previously pressed seam allowance and dislocated it. This is especially true if your iron is large or not very pointy.
You can use the stick as is (round), but it will tend to roll when you use it. If you or someone you know has a table saw, cut the stick down its length.
Making it half-round means it won't roll on the ironing board when you use it. It also means you get an extra one you can share with a friend. Or make the cut a little off-center and your stick will sit up off the ironing board enough that it is easier to pick up. (You can get your fingertips under the edge this way.)
You can also wrap the wood with fabric or batting, if you do not want to press directly on wood.
I got a closet bar and cut it into two lengths... a long one for strip sets, and the shorter piece for a pressing station at my sewing machine.
It works great.
...dany