First, make sure your account is private so you know who can see your pictures you can either decline or accept.Now you can control who sees what on your account.
Even though that your account is private,it still means you have to post sensible pictures as people can find a way to see them.
If someone has DM (direct messaged) and you don't know them or it's inappropriate there is a "Block user" and "report" button which you can always use in that situation
As you can see people have stories on Instagram but if you decide to upload on your story make sure its nothing too personal.
Make sure that if u are tagging people they are ok with you tagging them.
If someone comments something rude or mean or inappropriate you can delete it so they don't keep commenting and so you don't have to worry but do tell an adult if something does happen.
Make sure that if u do write down your password you don't leave it out somewhere so your account won't get hacked .
lastly, remember don't tell any one your details for your account and you can enjoy yourself on Instagram
The creator of this guide has not included tools