The quick brown fox jumps over the lazy dog
Everyone knows that sentence. It contains every letter of the alphabet so it's useful to keep writing it out if you're learning cursive or calligraphy or just want to try out different pens. But of course it can get tedious after a while to keep on and on writing the same thing so here are some more sentences that you could use instead.
The quick onyx goblin jumps over the lazy dwarf.
The five boxing wizards jump quickly.
Pack my box with five dozen liquor jugs.
Sphinx of black quartz, judge my vow.
Jackdaws love my big sphinx of quartz.
Amazingly few discotheques provide jukeboxes.