First off get a agent, why not it's free service to the buyer. The agent will go into two sets of negotiations for you. One will be for the price of the contract (the price of the home). It always helps with the negotiations if you are pre-approved. Let say you find the house you want. They are asking $200,000. Your agent offers $195,000 but, your not pre approved and another agent offers $190,000 with a pre-approved buyer. The owners already bought their new home and need to sell quickly. More than likely they will accept the $190,000. So, it is always better to get pre-approved not only for negotiation purposes but, also to know what your budget will be (how much home you can afford). You can also negotiate contributions by the seller toward closing cost, title insurance, survey and home warranty to be paid by the seller.  

     Second set of negotiations come after a inspection. All problems can be fix by the seller or renegotiated on the price. This will all depend on your situation. For example a VA loan, the buyer can not pay for repairs and some repairs have to be fix by the seller to be approved by the VA.

Third will be after appraisal. If it  comes back below sales price they will either have to come down on their sales price or have the buyer pay the difference in their down payment. Or just opt out  the sale.