I don't personally agree with using software to monitor activity for a few reasons. There are two main reasons for my opinion of this: It rapidly erodes the trust between you and your child, and I tend to stay away from any tech targetted at/for kids (or parents for the purpose of monitoring kids) due to the numerous scandals (insecure, data problems, whatever).
The single biggest influencing factor for online safety, in my opinion, is education. Explaining what the internet is, how it works, etc. _without fear mongering_. Present the dangers, and the benefits, without bias. The best way to approach it is by being honest. There are dangers, here's the reality of them, here's how you should deal with them, and here's when you can come to me without fear of judgement. The key here: don't try to "scare them straight" - it doesn't work. Just be honest.
More helpful than any monitoring is encouraging a home where your kids want to come to you with their problems, instead of hide their problems from you. In my (admittedly anecdotl) experiences, monitoring widens the gap between parent and child - not closes it. Don't forget that kids deserve some privacy in their lives, too.
In general, I think it comes down to "be a good parent". Be available, be helpful. Educate. Don't lie or overexaggerate to get a point across - no matter how valid the point. Ask about your childs day and try to pick up on non-verbal cues that something might be going awry.
The internet is out there, your child is going to find it. Help them make it through that, rather than shelter from that.
Thanks for listening to my tedtalk