Scissors, cross hop, heel to toe, and 2-step
Jump rope while crossing your legs in 4 different drills. First is "scissors" where one foot is forward and the other is back - on each jump the two feet switch positions. The second is "cross hop", in which the two feet spread out to either side then on each jump they alternate sides, crossing and uncrossing your legs in the process. The third is "heel to toe" in which one foot is jumping while the other is alternating stepping forward with the heel touching the ground then stepping backwards with that toes touching the ground. Be sure to do both sides. Do all of these for time or for amount.