If you have a trainee in a work context, where they're expected to soon be productive in the particular tools your company uses... get them started with those tools, point them to good instructional material, give them appropriate work assignments, and give them lots of mentoring (talk with them at beginning/milestones/end of each assignment, walk them through things they need to know that aren't in the materials, find the right balance of being available for questions but also getting them comfortable finding answers, etc.), and also get them started familiarizing with your organization's stuff and examples of good practices (e.g., reading select internal docs/code, monitoring Git commits, etc.). You'll also notice things they're doing or not doing, that you didn't think to mention before, so you can give tips as you see them. And it's important to be encouraging, not discouraging, even if you're encouraging them to work harder/smarter at something.