When you hire somebody junior in your team, there are few things you need to make sure of in order to have this person develop, perform and be more than a cheap source of labor.
Allocate time to support them. In small teams, this can be complicated, and yet a junior member is most likely not going to learn and develop independently, and surely that is not going to happen in a way that can be beneficial to the company. Give them the appropriate attention, guide them, if necessary match them with a mentor, or an advisor, somebody you trust and is committed to what you are trying to achieve. Invest in their learning (online courses are great, peer group even better), and be absolutely sure they are not feeling on their own on a difficult journey.
Set some boundaries to their responsibilities. And make sure what’s in the job description is achievable with the support mentioned above. It’s funny to see how many students or new graduates are made “managers”, or “specialists”, setting them up for failure already in the way they are presented. It’s ok to be a “junior”, or a “coordinator”, or a “responsible” for a while, and then grow the list of responsibilities as more confidence is acquired.
Understand the way you behave will shape theirs. Contrary to more experienced people, who might have their own style, their own work routines, their own rhythm, junior employees usually don’t have any of that. You have the chance to help form such things, and you better do it consciously and with a clear plan. Think about the type of person you’d like to have in your team five years down the road, the type of colleague you’d be glad to work with, and then be mindful about how you measure their performace, how you talk to them, deliver feedback, give them guidance.