highest and best offer

[Bryan P]

I put an offer in yesterday and the listing agent is now asking for my highest and best. He's being kinda shady because first he said there were no other offers but one was coming in soon, then he said another offer came in about two weeks ago. Is he lying about the multiple offers just to get me to go up? Also how can I make my offer look better besides a higher price? More earnest money? Quicker closing? Please help, I need to give my offer today.