Your only intelligent offer is one based on the comps. If you love the house you may be willing to raise your offer, but be aware that the appraisal my not workout. However, besides comps. some appraisers also look at other factors includng condition, contingencies, and your personal needs.
As far as lowball. NEVER feel you will insult the owner. An seller's motivation changes constantly. One minute they would be upset about an offer, the next they need to take that offer. Today, owners should be ecstatic to get any offer. It may not work out, but it starts a dialogue. Buyers still cannot steal a home, but if your agent represents you in a way that gives validity to that offer and the seller's agent has been true to their client of where the market is, coupled that with a seller that wants to sell and a buyer that wants to buy, you will come to a meeting of the minds.