Are there any Sifre Musar that give advice on how to become more patient? If so, can you bring a few points on how to do so? Please cite sources.
I suggest Gateway to Happiness By Rabbi Zelig Pliskin
The lesson in patience which I still recall - 25 years after having last read - it is the following:
Conclusion: it's our perspective that makes us impatient - and we do control it.
This is one of the rare occasions when he uses gruesome examples, but it sure is effective. Gateway to Happiness is a book worth reading. So are his other books.
Disclaimer: I have no connection to Rabbi Zelig Pliskin, though I have met him and thanked him for his advice.