Learning to parry correctly is one of the hardest parts of the game.
What Evolution169 is talking about is what we usually call a buffer parry, you can buffer a parry into a normal or another input.
Buffer parries are used more than guess parries for obvious reasons. They aren't REALLY an option select because if you do a normal you actually eliminate the parry frames.
Now there is one option select that does work, and that's buffer parry into kara throw, it's called SGGK, what happens is the throw will come out if they block and if you get the parry, the normal you used to kara comes out instead of the throw. It's a bit complicated.
Buffer Parries are what you should be using when pressuring opponents and doing stuff like dash up throw.
Something that you shouldn't do is parry on wakeup or fish for a parry mid screen unless it's a read or you understand the matchup.
A good way to practice parrying is start with just trying to use it in matches, think about what your opponent wants to do and what his options are from that range and buffer.
Trying to be sick and parry everything they do, IS NOT POSSIBLE.
Another thing to try is parrying special moves, over and over. That is what you'll be parrying a lot of the time. For instance, Gouki tatsu, you want to be able to parry it if you accidentally crouch the first couple hits. Red Parry will come with time. It's just about negating something that is already happening at this time.
Preemptive parries in high level are almost always buffers, no one reaaally thinks, alright I'm gonna do a low parry and get a sick combo. They say I'm going to buffer a low parry and try to make him block this crouch short because both options are good for me. Hopefully one gives and you get some damage out of it.