That's one of the most difficult things you can do, is ask for a pay-rise. Another one is resigning, that's a difficult thing, but focusing on asking for a pay rise I think, firstly you've got to have information about:
How did you perform in the past twelve months, in your role?
Did you have KPI's? (Key Performance Indicators) against which you performed, and how you fared against those;
What you're looking for, in the future, with the organisation.
So you don't just go in and say "I think I'm worth more money." You actually sit down and think objectively about the work you've done in the past 12 months, how you went, what you're looking for in the next 12 months.
And then, if you're clever, you get on the Internet and you'll come onto to something like LinkMe, and you'll compare yourself to other people in similar jobs and you'll have a view, an objective view, to talk to your boss about. About where you compare with your peers, doing similar sorts of jobs, what sort of money they're looking for.
You can look in the newspaper, look at job advertisements for the similar role that you're doing now, and see what salaries are being offered. So, if you're with a small company, and they're offering salaries similar to yours in small companies, but they're offering more money in medium or larger companies, you can get a perspective on where you sit in the job market.
Another way, before you ask your boss for a job, is to go to a recruiter and talk to a recruiter about what you're doing now and what you might be able to get in the next move you make, or if they moved you in the same role, what sort of salary you would be getting there.
So, in other words, plan and think objectively.
Show your boss that you've understood what you're doing now, what you want to do in the future, and you understand your value, and so you are confident.
I always say, information is knowledge, knowledge is power. So when you talk to your boss about getting more money, be professional about it. Be objective. Give him, or her, information to allow them to make a decision to say yes for you, because most bosses are nervous about "Oh, I know I've got to give you an increase, and we'll make it CPI - just a cost of living increase". But you should say, ok - cost of living is 5 percent, but I think I've performed over and above most people and these are the reasons why, and this is what I think I should be getting.
So, make it easy for your boss to give you a salary increase.