One question shows your interest and gives them a chance to say as much or as little as they want. It indicates that you care and want to know how they are doing. Too many questions can make them feel like you are pressuring them.
Offer opportunities for them to work outside of practice. Offer, not push or demand.
Iʼll drive you to the gym if youʼd like to work out. Would you like to go to a speed training camp?
Iʼll be glad to check out traveling teams if youʼd like to play.
If they say no, then drop it, and maybe bring it up again at another time when they express a desire to improve their skills.
Be at as many games as you possibly can. Itʼs understandable if you canʼt be at every one, but the more you are present at your childʼs games, the more you communicate your support. Your presence may push him to work harder and play his best.
Notice, and offer casual praise for his hard work. You may be jumping up and down inside that your kid is pushing himself and working hard, but you gotta keep your cool, especially if we are talking about adolescents.