Time Out... Too Soon?!?!?!

Abby is active. Like you have to watch her 100% of the time or she is getting into something (everything) before you can stop her. She loves to climb, taste everything seh gets her hands on, and learn about everything around her. In lots of ways I lover her adventurous spirit, her independence, ehr desire to learn. But not only is it messy it is somewhat dangerous. At her doctors appointment a couple weeks ago he told us that it is time to start introducing the word no. Not to over do it, but when she is doing something we really don't want her doing then to slap her hand and firmly say no. He says if you do it right she should cry - not because you hurt her but because she doesn't like you being mad at her.
Abby has some behaviors we really want her to stop - chewing on power cords, eating plant leaves, getting into Penny's food and water. Last week she kept getting into our plants. I had told her a few times not to (very firmly) and removed her from the situation, but she persisted. So I decided I better do what the doctor said and I smacked her hand and firmly said no. There were tears, but not from her. She looked at me and smiled and then reached for the plant again. Clearly I was not affective at that form of discipline and it broke my heart. (She had the same reaction when Ryan tried it.)
Failing with that but still wanting to teach her (a firm no is just not working either) I decided to try putting her in time out. I put her in a laundry basket. At first she didn't mind but after awhile she gets sick of it and starts complaining. But still I am not sure it is effective. She still gets into Penny's water multiple times a day. She was in time out 5 times on Friday.
So, does anyone have any suggestions. How do you discipline your babies? I just want to keep her from doing things that are very destructive or harmful. Is that too much to ask?