Something I've started to do in practice mode is pick Raiden, and then pick Jacqui as the opponent. Then set standing mode to duck, block mode to random attack, and reversal mode to on, with Grease Kicks being selected since it has 8 frames of startup, which I believe if done as a reversal is the equivalent of a 7 frame move. Then I practice hit confirming F3 into either block or 243, trying to get the 243 jail. You can even go a step further and work on hit confirming the 243 into a special move as well.
Edit: You can also use this same setup to practice D3 and hit confirm into F3, and then into 243, just to keep adding layers. D3 technically jails 243, but it's a tight link (D3 is +12, and S2 has a startup of 11), so I find it easier to try and have my offense up close revolve around setting up F3 with either D1 or D3.