What advice should i give for a person with self destructive thoughts? If someone is really depressed and having self destructive thoughts and behavior what can i do to help such a person?

Is there a good meditation for such a one?

What kind of advice will it be best for a such a one?
Metta meditation can help as it subdues hatred which is a major cause for suicide.
Other Samatha meditations like Anapanasati can help to attain extremely pleasant states of the mind like the Jhanas where there's no depression. 
Vipassana can be practiced to make one not react to unpleasant feelings or thoughts and eventually achieve lasting peace.