If you are using LaTeX on Unix, the problem is that, by default, LaTeX uses Type 3 fonts.
Since most users have a tendency to use the default settings, then Type 3 fonts will be used by default.
Therefore, if the first line in the LaTeX file is something like:
then Type 3 fonts will be used. But if you modify this line as follows:
then Times fonts will be used (which are not Type 3). If there are mathematical formulas in the text, it is better to use:
Afterwards, you just have to generate the dvi file from file.tex (laTeX file),
the PS file (dvips -o file.ps file), and the PDF (ps2pdf file.ps). After changing the fonts, you must review your
paper very carefully to ensure that it still meets layout and page limit requirements.