This question comes to me from coaches who want to get in on the many benefits of goal-setting for individuals and teams. While the answer is an easy one, many coaches fail at following through because of the necessary time commitment. However, the best coaches make time.
So, where to start? When researching 'how to set goals' you will quickly be overwhelmed with a hundred different types from SMART goals, to process-oriented goals, to performance goals. Everyone claims to have that secret sauce that will give your goal-setting an edge over the rest. Now my usual advice is to find what works best for you and run with it, however in this case we're trying to find a balance between efficacy and simplicity - after all, the aim here is to implement this team-wide.
First things first, come up with your timeframe. I like to split the season up into chunks - the easiest being a mid-season and end-of-season goal for each athlete (if time isn't a constraint, cut the season a few more times to add more check-ins). Next, it's time to have individual conversations with each player on your team. These can be a few minutes, but make sure they are meaningful and that you give the individual your entire attention. This may be hard for you - coaches often tell me they simply don't have time, but that typically translates to, "I've never been one-on-one with each of my players and it scares me." My response is that a sports team is more than just a sum of its parts. Coaches that truly have a personal relationship with each player will inherently elicit greater work ethic, drive, and determination on the whole.
During that one-on-one, ask the athlete what they feel is the strongest part of their game and what area needs the most work. It's vital that you don't try and "guide" them here (a struggle for many coaches to take off their coaching hat for just a moment). Listen to what they have to say and ask questions, especially if you feel like they are just trying to appease you by telling you what you want to hear. After they tell you what they think they need to improve, transition the conversation to how they can improve that area and what you can do to help them in their personal journey. Make sure you tell them that you'll be having this conversation again in a few weeks (mid-season) to see how they're doing - your delivery is key here as you don't want them to feel like you're going to test them in a few weeks, but that these check-ins are a positive thing that will help them become a better athlete.
Once you've had this goal-setting meeting with each player, the work really begins. I suggest having a cheat-sheet with each player and their goal handy so that you can review before practices/games. This is important as you want to bring up players' goals often - congratulating when appropriate and guiding when necessary. I cannot stress this enough: athletes of ANY AGE recognize when their coach has taken a personal interest in their sport journey and it makes a massive difference in their intrinsic motivation.
My final piece of insight: many coaches ask me if they can pass this player-development strategy to their assistant coach. Sure you can, but ultimately these are your players who you're asking to give you everything they have. I always see more success when a head coach invests their time. After all, the best coaches make the time.