After setting the offering plate (of banana, yoghurt and gur) before the silas, I place 3 drops of water into my right palm...

...show Ram-bija mudra and chant"Raam-Raam-Raam"...

...and then show Tham-bija mudra and chant "Tham-Tham-Tham." This procedure burns off impurities and nectarizes the offering.

Cakra and dhenu mudras, 8 times chanting Deity's mula-mantra, then matsya-mudra. Then I ring the bell, chant the offering prayers, first line of gayatri, and chant Purusa-sukta.

This is a general mudra. One could use it for any item. I show it when it is time to offer water after naivedya.