If you are currently employed and want a raise, start by being prepared. Gather your salary survey information, recent performance appraisals that document the job you're doing, and any other relevant information. Be aware of company policy regarding compensation.
Some employers are limited by budget constraints and can only give raises at certain times of the year, regardless of the circumstances.
Have a clear idea of what you want. Determine the salary range you're looking for and justification for the increase and have both ready to review with your supervisor. Be flexible. Would you consider an extra couple of weeks vacation instead of a raise?
I know someone who has regularly taken time-off instead of money and now has six vacation weeks a year... Then, ask your supervisor for a meeting to discuss salary. Present your request, supported by documentation, calmly and rationally. Don't ask for an immediate answer. Your boss is mostly likely going to have to discuss it with Human Resources and/or other company managers.
Despite your best efforts, there may simply not be enough money in the budget to increase your salary or compensation package offer. The company may also not want to create inequities by paying one person more than others in a similar position.
In that case, you can at least know you tried. Plus, if this is a job you really think that you're going to love, consider whether the company culture, the benefits, and the job itself are worth it - regardless of the salary.
According to the AgCareers.com 2015-2016 Agribusiness HR Review, the most predominant month for conducting salary reviews is December in the U.S. and January in Canada. The most predominant month for implementing increases is January for both.