|If you were to go to a sales meeting, would you get into an argument with the customer to convince him or her to buy your product? Probably not.|
When you are asking for a pay increase, think of it as a sales meeting. Start by picking the right time. Avoid periods when your manager is busy or upset, and look for periods when you have been particularly successful.
During these meetings, be sure to make many comments that will generate agreement from him. The more he agrees with what you are saying, the more likely he is to say "yes" later in the discussion. Try to use words that have a strong positive emotional charge for him, such as "profit," "achievement," "success," and "excellence."
You can certainly bring in some salary comparisons, but you should also have an idea of the value that you add. Take a look at your skills, education, experience, and performance and let your manager see the clear contribution that you are making well in excess of your current salary.
As for the delay of a month and the rumor that your manager ignores these requests, the best step is to keep following up. After all, asking for a raise calls for sales skills, and successful selling calls for persistence.