Sienna Miller says the most important lesson she's learned this year is hold your cards close to your vest.

She explained: I've got a huge mouth, especially when it comes to my business. But I've realized that if you start talking about things, you open up a floodgate. She declared this in an interview for Life magazine, in the December 30 scheduled issue.

The 24-year-old actress is engaged to Jude Law, with whom she co-starred in 'Alfie'.
They became engaged last December. Law had divorced his wife, fashion designer-actress Sadie Frost in October 2003. They had been married for six years and had three children.

Miller and Law's relationship seamed to fall apart after Jude admitted to having an affair with his children's nanny and publicly apologized for it in July. But the couple got back together.

Sienna also told the magazine: I find it odd that people ask me things like, Why did you take (Jude Law) back? I don't regret anything.

'Casanova' opened in U.S. theatres on Christmas Day. Miller was asked who is a modern-day Casanova in her opinion and she replied: I don't know. . . . People think I should be an expert on love, and I haven't got a clue.