Dear Charles,
Do Medicine Buddha puja every day for the next week at least. From the day your father passed away, try to do Medicine Buddha puja every day for forty-nine days, or at least once every seven days for forty-nine days.

Print a nice photo of White Tara, as large as you can, and have it blessed on the same day. Do this on the next eighth day of the Tibetan calendar.

Try to make longlife deity tsa-tsas every day, or organize for someone else to make them, until you have made the number equal to his age (approximately 90 tsa-tsas).

This is my advice.