Actually, there should be a comma between the greeting and the name: Hello, Maria. Hi, Maria. A possible exception would be e-mail, where punctuation is omitted to an ever-greater degree. An exception to the greeting rule is "Dear" at the beginning of a letter or message: Dear Maria, Also at the beginning of e-mail: Hello Maria, [Note: this last sentence got cut off somehow. E-mail seems to be forming its own rules - it's not wrong, just the trend] Reference: http://www.businesswritingblog.com/business_writing/2006/02/using_commas_wi.html

put comma "Hello Maria,"‏ and then start addressing :) :) like Привет Maria, Надежда Вы делаете хороший. .... :)

It is acceptable by now to use "Hello Maria".

No. Full stop at the end. Hello Maria.

Ur wish