Best way IMO and how I learned other job's openers and rotation is have the opener opened up on a second screen (phone, secind monitor, overlay program etc). Try out the opener until you get a feel of it against a dummy. You don't even have to follow the opener exactly and reset everytime you screw up just keep at it until you get the feel of the job's opener and rotation execution, then adjust accordingly to the correct opener once you know where your buttons are.

Once you get the basics, every content you queue up for (except savage unless you are very confident) go in as that job you are learning. This will help you immensly learning the job overall than just smacking a dummy over and over with the same opener. As in actual content fights are way longer as knowing your opener is not the same as knowing your job very well. Because fights are longer you can put in practice pseudo openers while dealing mechanics and learning uptime and at the same time getting better at not tunnel visioning.

You are already doing a very good job by asking and wanting advice. Be sure to check out resources like The Balance to improve even more. Keep at it!