Hi I.,
At this age, toddlerhood, limitation is the most proactive approach. This means doing more childproofing: latches for the off-limits drawers in the house; using gates, doorhandle covers and other safety measures to prevent your children from getting into rooms which require parent supervision. (Bathrooms, esp, are unsafe for little ones unattended. And they do make latches for the toilet, to keep it shut.)
For what it's worth, in my opinion, prevention is optimal and then, distraction and redirection to follow up. When your child has something inappropriate in hand, you can offer him something else as a trade. "Oh, that one is for Mama, it's not meant for you. You can have this one." Yes, our children need to learn boundaries at this age, and we are also modeling how to make those trades when they are ready to do it with other children, so we must be thoughtful in showing them how to do it kindly. (This means no grabbing things forcefully out of their hands, which only teaches them how to grab.)
You don't have to go overboard either, just be clear and simple with your words when you are giving him guidance and use a serious voice, not a lovey-mama voice. You can be gentle and firm at the same time. I also caution parents not to fall into the "asking trap", which is where the parent uses a question instead of a direct request (this looks like 'Are you ready to stay out of the silverware drawer?' instead of "It's time to close this drawer. Here, you can play with this.") Our toddlers are very confused by questions, so just know your own mind as to what you want to do and help your kids along with simple "It's time to..." statements.
I haven't read any other posts, but will say preemptively that, at this age, I've found time out and other punitive techniques to be more distracting and less helpful than just helping the child to move along. Making them sit down only starts up a power struggle, when so often we can just teach them what is okay for them to play with. Once again, prevention is the best medicine..if we limit their access and don't fall into the trap of expecting toddlers to have self-control and self-regulation (which they don't have the maturity to possess), we help to teach them where they can be and avoid the stress and struggle that allowing them to be in forbidden places can bring. Best wishes!