In this video Sarah meets Marcia to negotiate on some of the details in her contract.
Companies are often used to people negotiating so, as long as you're realistic and polite, and can justify your requests then it's likely that you will get something out of it.
Negotiating is more than just about your salary though, you can also negotiate on, for example, monthly salary, bonuses, car allowance, pension contributions, healthcare contributions, number of days holiday or even future salary review dates.
Some companies have fixed policies about benefits, depending on the level of the position. This can make negotiation tricky, as the employer may literally have little say over the package. This was the case with Marcia who was unable to offer Sara a higher salary or more days holiday.
If this is the case, simply ask them where they could be flexible - and negotiate from there. Sarah was successful in getting added to a bonus scheme and changing her start date through her persistence.