Definitely knife skills, and like
Mountain Cat says, not the super-speedy restaurant kitchen style, necessarily, but just being competent, knowing how to get uniform slices and dices, how to mince, how to julienne, and all while keeping your fingertips intact.
Knowing how to reduce a liquid, and along with that, knowing not to be afraid of the heat, when it's called for. Know the difference between a simmer and a boil, know that, yeah, sometimes you do need to use high heat on a pan.
Develop the discipline to practice mise en place as much as possible, even when it really feels like you don't need to.
Two things that'll set you on the road from basic to advanced: follow recipes when starting out, as closely as possible, then judge the results, and as you get some familiarity with different ingredients, don't be afraid to change it round to suit
your tastes, and second, pay attention to what ingredients look like/feel like when they're done - how much resistance does that boiled potato give? What's that steak feel like at rare versus medium-rare versus medium?
Also, take care of your stuff. Keep your knives sharp, your pans clean, and your wooden boards oiled.