Avoid getting caught up in the heat of the moment. You're making a contract to purchase a home, which will legally bind you if the seller accepts. You also will submit a deposit with your offer, which is only refundable under certain conditions.
Do Your Research, find out about:
Prepare Your Offer
The seller may accept, reject or counter within hours or days, depending on the quality of your offer and the seller's desire to sell. You can then accept the counteroffer or "counter the counter." Once the seller accepts, a third party (a lawyer or an escrow or title company) completes the transaction with your lender.
Below are some suggestions and ideas you may want to think about prior to making a commitment to purchase a new home: