Negotiate or Accept

If you wish to negotiate rather than just accept the offer you could:
Call the hiring manager and say, “I’ve had a chance to thoroughly consider the offer. I’m excited about the contributions I can make and I think it’s a really good fit. There are a couple of areas I want to talk to you about, and once we get these resolved, I’m ready to get started as soon as possible.”
Ideally you should:

• Confirm the items on which you are in agreement.
• Emphasise the contributions you are prepared to make to the company, supported by your past-achievements.
• Address each item to be discussed with the most important first, usually salary.

If the base salary is not high enough, focus on the level of responsibilities and contributions to the organisation that you can provide, then ask if the job can be re-evaluated to the next higher level. In this way, the salary you are asking for, which may be too high for the current level might become a reasonable base salary for the next grade above.

Remember the company needs to keep the offer in a competitive range for the position. Companies must pay a competitive salary to attract and retain competent people. If there is a significant difference between what you are seeking and what the company is offering, the position is probably lower in responsibility than you want. The fit may not be right. However, the company wants you to join them, so you may be able to get the job expanded. It is worth a try.

Repeat the cycle, if you deem it to be necessary.