Your first attempt at brush lettering should make you feel successful. Here's my advice. Start your journey by working as though you're a righty. This will help you understand the basic marks you will be making and better understand why you can't make them when you're writing forwards.
Practice making some simple marks on your paper from right to left.
Righties drag that pen behind their hand and the hairline upstrokes are simpler to accomplish. Similarly, the beautifully thick shaded downstroke feels like you're laying a solid foundation with easy pressure on the broad edge of the brush tip. When you combine the two pen strokes, you feel the exact way a righty feels. The pen naturally makes this mark without much tweaking or effort.
Don't be upset. I know. It's a tough pill to swallow. Right-handed people naturally make these marks that I struggle to produce. WE STRUGGLE. We're in this together! Don't quit on me.