I'm inclined to agree wiht posters who say to make a significant bid, assuming its within the limit you'd set yourself for the property anyway.
Myself and my OH recently outbid someone by €20k in one fell swoop. We really wanted the house and we knew roughly what the vendor wanted to get the deal done. The under bidders offer had been on the table for a little while and was neither accepted nor rejected.
We saw the house very last minute and didnt have our finance in order (we were in the process, but didnt formally have the AIP paperwork in our paws to prove it). We offered €20k on the basis the the vendor would need to wait 1 week for our paperwork. We knew because our bid was a bit complicated that we'd need to get his attention, so we decided to try to knock the other bidder clean out and it worked.