As far as I can tell this letter in cursive is best written starting at the upper left point, so that when you curve down, your in position to do what I call the thunder bolt. However most letters end at the bottom so that may mean the proper way to start the letter is at the lower left point. Of course I could do it however I want, but I just want to do it however its traditionally taught.
Check out this website: http://www.russianforeveryone.com/RufeA/Lessons/Introduction/Alphabet/Alphabet.htm
When you press the play buttons, it shows how the cursive lettres are written. The Ж needs some exercice, but once you got it, it's quiet easy. Good luck :-)
The proper way is to start Ж from the upper left point indeed. Most of the letters ends at the bottom and starts at the top, so you can connect any two letters with one simple stroke from the bottom of one letter to the top of the next, thus making your handwriting smooth and contnuous with up and down waving movements of your hand. However, that is what makes handwriting difficult to read by foreigners (and in many cases even by natives).