Employers want their new hires to feel a sense of loyalty to the company, and it begins with the hiring process. It's worth their while to respect you and be flexible in addressing your concerns and needs. If this is not happening, you may want to rethink what it would be like to work there. Do your research and be reasonable in your requests. It is okay to ask for more than you are initially offered but be realistic.
Most employers do their homework and develop offers they feel are justified by the market.
While they are open to counteroffers and to negotiation, they also expect them to be based on objective data, not emotions. Otherwise, they will not be persuaded to move. When they give you an offer, do not just react by asking for more money . Instead, think about the whole compensation package, not just the base salary. If you want to improve the offer, bring up all of your issues at once and get them on the table.