Before and during the interview
Do a little research before the interview. Acquaint yourself with the pay ranges and benefits of the company and compare them within the given industry: you will also learn other useful information about the company and its competitors. Then consider what you want from work, in terms of both pay and benefits and opportunities, mobility and flexibility.
Never start an conversation about pay too soon. First, thoroughly check to what extent the organisation meets your expectations and what value you can offer. This way you will gain greater security and a stronger negotiating position, and you will not, for example, unnecessarily underestimate yourself just for the sake of getting a job offer.
When an employer asks you directly for a figure, use your initial research and talk about standard salary ranges, not specific numbers.
At the time of the offer
Try to mention your specific idea of pay before the employer mentions it. This will start negotiations from your position. If the employer offers the job and salary at the same time, do not commit yourself too quickly if they are interested in you. Take time to think. In addition, if you have had interviews with other companies, inform the potential employer of a competitive offer. Find out if this might speed up the interview process or give you better conditions.
If your employer can't offer you the required pay, think about other valuable bonuses and try asking for them. For example, education is a great benefit that will further increase your value in the job market.
You could secure a better bargaining position by quantifying your value: for example, state how much money you saved your current company or how your projects increased sales by whatever amount.
You can also ask your employer to review your salary after six months rather than a year, or for a year-end bonus if you have made a certain amount of money. You will thus show you believe in yourself and are committed to bringing the values you proclaim to the company.
Being able to negotiate a salary is not something you learn overnight but it is definitely something you can learn. Work on it.