Don't worry, you'll be fine.
I've been fooling with bikes for over 50 years. I dab whatever grease I have handy when I install pedals. In all that time I've never had a pedal that I couldn't get off.
FWIW, usually the left pedal has an "L" stamped somewhere on the spindle. Other pedals have a series of lines stamped into them to indicate the left hand thread.
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My greatest fear is all of my kids standing around my coffin and talking about "how sensible" dad was.