When she was young (<1yr), food throwing got a warning and a reminder of the correct behavior ("We do not throw food. You may give it to mommy or put it on the table.") then on the second time a warning, the correct behavior, and a consequence ("We do not throw food. You may give it to mommy or put it on the table. If you throw food again, you are getting down from the table.") then the third time, a review and the consequence ("I said that if you threw your food again, you would get down from the table. You threw your food, and now you're getting down from the table." followed by me physically getting her out of her high chair/chair and putting her down on the floor). Now that she's older, one warning, then the consequence. And hey, if she didn't bother to finish dinner, oh well on her part.
Toys - I ignore it if it's a toy she's allowed to throw (soft toys) or take it away if she's not. Again, at 2.5yrs old, I don't give lots of warnings about these big rules that she's had a lot of experience with. When she was younger, I'd give her the standard "warning and appropriate behavior", "warning, appropriate behavior, consequence", "consequence" sequence. Also, in the case of throwing something when angry - or any other expression of emotion that will some day be inappropriate - I try to give her an appropriate way of expressing her emotion that will still satisfy her need to express herself.