Do you really stick to the 70% rule?

[Ryan Adams]

I have been trying to pick up a property for a fix and flip locally but am having a difficult time.  I've put in a few offers but they are just languishing.  I'm looking at properties with arv ~175, asking price ~135 needing about 25 in repairs.  My initial offer was 80 cash, as is with inspection, fast closing.  I'm not even getting a reply.  While that might be a tad low, I wanted to have some room to move up when they countered.  If I offered 95, I'd be pretty much spent and couldn't negotiate.

This is still my first deal so I wanted to make sure I had a buffer for when I inevitably miss something.