When negotiating prices and details of the contract, make sure you work out who has control of the market at this point in time (prior to the time of negotiation).

If you are in control (e.g. if the market is currently flooded with houses similar to the one you are looking at) push hard to try to get what you want. If the seller is, try not to ask for too many allowances as the seller will quickly try to find a less challenging buyer.

Once you have done our research on prices in the recent market, bring evidence of these to negotiation talks. This gives you more ammunition with comparing prices to what you have been offered.
Consider using immaterial goods or services as bargaining chips. This can include things like moving a settlement date forward or back according to the sellers needs, or them including furniture or artwork in the price.

If any changes are made to the original contract, make sure they are documented and written down. Anything that isn’t written on that piece of paper will not count at a later date.