The 5 main ways to get into an omoplata attack to either sweep or submit your opponent. From https://www.grapplearts.com/omoplata. The 5 main mechanisms for entering into the omoplata from the guard are:
0:25 - Swinging Entry
2:02 - Turret Entry
3:17 - Racking the Shotgun
5:14 - Crescent Kick
6:19 - Rubber Guard Mechanisms
Just to be clear, these are not the only entry mechanisms for the omoplata; there are definitely others including rolling entries, spinning entries, entries from the top, etc.
Also the divisions between these entries are not always crystal clear; sometimes two or more mechanisms will blend together when you're doing them in the real world against a real opponent. But learning the 'pure' style of each is still useful because it'll allow you to mix and match more effectively later.
I hope this helps improve your guard game!
Stephan