Well maybe you can set the ISO higher then 1600 then its possible that you get some good pics, you just have to try it ;) And what camera do you have?
Yea try to not get trees or building in the picture, it only takes light away that you can get from the stars
And is ISO 720 your max?
You sometimes really have to drive a while and look for a place where the sky is not lit up by some streetlight or airports or whatever
And you focused the threes, try to focus a bright star, or a light which is far away
And yes it's tricky, these arent by first nightsky pics i did ;)
E: here my progress
I started with this:
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Then went to this:
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Then to this:
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And this is my best pic so far:
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