1. Like all junior engineers they will need help. Make sure that there are multiple senior engineers that are both able and willing to provide guidance.
2. Try to hire from bootcamps that use the same tools that you do. If they've learned javascript and ruby on rails, and you're a python shop start them on javascript work for the first few months. If you're not aligned on the tools you're going to have a bad time.
3. If this is the first junior hire or first bootcamp hire, consider trying to find a bootcamp grad that's been out for a year or so. Ie look for one trying to get their second job in the industry. This will reduce the amount of handholding that you should need to do.
4. Have standardized technical questions or exercises. This will help you find the ones that have really learned their technical skills.
5. Not all bootcamps are equal. When you find one that's producing good candidates, its worthwhile to try and partner with that bootcamp.
Eventually if you continue hiring bootcamp guides you'll end up with a strong learning path for them.
I like to compare bootcamp grads to straight out of college hires. The former are going to be familiar with a set of tools that you're hopefully using including git. They will NOT have a strong background in theory. This contrasts with new grads who have the strong theory, but may not be able to use git and probably don't know the framework you're using. Depending on what you're hiring for, one will make more sense than the other.
There are always exceptions but I generally try to steer clear unless I just need someone to knock out CRUD APIs or simple react frontends.
If someone has a strong math/science/philosophy education, however, combined with the bootcamp then I'll sometimes take a punt.
if your willing to train them it's great as they have some knowledge. you should be able to get them quite cheap too. as most struggle to find anything.