Mine aren't that old yet but I think these are important:
Talking to adults, being polite, being able to form opinions about things and being able to defend them. This really just means you have to talk to them and listen to them a lot!
Learning how to make conversations with people you don't know more generally: e.g. by asking questions, listening to the answers, and following up on them.
Planning and organising. It's so helpful through life to be organised, so get them started with good routines about doing homework at certain times, getting everything ready for next day, planning longer assignments in stages, planning revision for tests. My 12 yo is struggling a bit with this, but I want to help him get things organised so when he goes to university he feels on top of things.
Positive thinking. Ask them to tell you at the end of the day what their highlights were and what they are grateful for. Tell them yours. Doing this every day is life changing.
Doing some kind of sport or exercise every single day if you're not actually ill.
How to cook 10 different things (proper meals not cupcakes or whatever). I am working on this.
Not lying. Insist on honesty and try not to blow up at them when they are honest!
Being kind. Point out examples, make suggestions, explain why.
And I also have invested quite a lot of time and money in things like swimming lessons so they can do the strokes properly (my mum always regretted not being able to!), tennis club so they will always be able to play. Things like that to give them a boost when they are teens and older. But it depends on your financial resources and their inclinations.