I would also recommend a book:
Positive Discipline: The First Three Years-Laying the Foundation for Raising a Capable, Confident Child
You can borrow it from the central library. (if they have only one copy, then it's with me now

)
My boy is 14 month old now, he is an active walker and just want to have his little hands on almost everything, and sometime have a taste with it too. He can't talk yet (only papa, mama, gama and the outer space language), but he can understand some words and simple instructions. I think he does understand "NO" something, but may not fully graps the concept... This book has been interesting to read, I recommend parents to take a look.
After reading the book, you may have more empathy for your baby's so called naughty behaviours, thus better understand how to start the positive discipline, with some useful tips/ techniques suggested in the book.
However, I guess there's really no one effective discipline not taking time and patience to make it work, so do what are recommended in this book. Afterall, these are all for long term and once you grasped the ideas, you can probably do it well without sweat.
I also a fan of Supernanny JoF TV series (showing on NOW TV's BBC lifestyle at 10:05pm HK time every Monday), and I have learnt about the naughty spot technique, houserules, not shouting to kids when you don't want them to shout...and etc. The Supernanny techniques are not so applicable for my 14 month old boy now, but definitely good to be kept in my brain for future reference.
Happy parenting to all! Hope there's no spanking on their cute little butt...I just can't lay my hands to that.