Naaaah dont do exactly what DanD is saying
look (not flaming, let me explain)
Like the example dand gave you there are a lots
look, try this with ken, as a blocked chain, use cr.short then st. forward, after this just tap down. It works a lot, yeah buuuuuut theres a problem when you do this script based parries.
You become predictible if you dont… like, Damm I cant explain it, like feel it.
I used to have a whole theory for this
I call it the “After Hits”
After watching some videos I would do most of parries like the one I pointed or DanD did, script followed (by this I mean you just tap down after a particular move, for some reason your opponent will just poke after them).
They worked for some time, but they bcame useless after some time.
After some time I came out with the After Hit theory
After using a lot of times these tap down moves I found out that my opponents will know exactly how to bait me with them. I realized I had to understand why they poke like that.
The thing is that every player (at least most of them) is looking to have control of the round. The basic strategy for every game is not to fall in your opponents gameplay.
Therefore, whenever you are putting presure on them, they are looking for even the smallest opening to stop your mixup.
Heres when you use an after hit
Have you’ve ever seen Daigo?
Everyone say this guy is psychic and shit. Naaaaaaahhh , he is nothing like that.
He didnt read your mind, he made you do what you did and punish you for that.
The After Hit theory I found is basically this, You give your opponent an opening, a really atractive spot to stop your pressure, and you parry.
The parry is usually low because people is most likely to respond with their fastest poke. (wich is most likely a jab or a short wich can be parried low).
This doesnt work only on the offensive, when you are the one being pressured, you can give your opponent the idea that you’re just there standing, and then you see it, he is seeing you there taking the mix up like a bitch, and now, in order to make you stand still he will use his fastest poke like a crouchin jab or something like that.
PARRY!!
You understand me?
You atract it, you dont just tap down just because, in these 2 examples you can see it, with Ken’s st forward is even more clear, you give an atractive spot to atack, but some people just tap down without knowing why, just cause they saw it on a video or on a post in this case.
Thats why I call it an “After Hit” it comes after something YOU did.
If you have these things in mind you can come up with thousands of situations where you can atract pokes, Im so hated in my area because of this 
I uploaded a few videos whre you can see that with my friends (since we know each other) we have to play reeeeeeeeeeeeal safe, so you wont see as much low parries as I would apply with people that dont know me.
Use this in your adavantage.