The linked slidedeck holds many tips, of which I list the most interesting to me below

DATA and END

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The __END__ keyword tells Ruby where a file ends – but you don't have to stop there. Any text you add after it is accessible via the DATA object.

Running the attached example file data.rb prints:

DATA is a File object to everything in the current file after "__END__"

No braces needed for 'special variables'

@instance, @@class, $global = [ 'instance', 'class', 'global' ]
puts "#@instance, #@@class, #$global"

Infinite arrays

ring = [1, 2, 3].cycle
p ring.take(5)
# => [1, 2, 3, 1, 2]

I haven't made it beyond trick #44, it was just too much for now.
But you, go and add your favourites!