Every situation wlll vary.
It seems like a few years ago one could offer alot less than currently.
Discuss with your Realtor to find out if the home is priced right to begin with. If so, it's wise to not take a chance and offer close to full price. If the home is overpriced - ask your Realtrto find sales comparables to demonstrate that a lower price is reasonable. As a Realtor, I can pull up sales comps which will show the average difference between asking price and the actual sales price.
That gap is shrinking from over 10% a few years ago to less than 3% and that is a very general statement.