L.O.
E.:
You may want to try another way than saying NO. Babies at this age do need to learn their boundaries and will more than not cross the line in order to learn. They are smarter than we can ever imagine. I suggest to show him, with your actions, the reason why he shouldn't go near...for example the electric outlets...you go near it and say "OUCH"!!! and pretend to cry...then explain to him that this is electricity and can hurt him if he touches it.
If what he is touching or going near is something that you have the ability to put away for a short time, than do it. This is called child proofing and will only be for a short period of time.
Babies also look for attention whether it is good or bad...so you may want to spend less attention on what not to do and spend more attention on the proper things to do.
Good Luck:)
L.