Take a few grains of unbroken rice in the palm of your left hand
Apply a few drops of ghee to the rice.
Exactly at sunrise utter the first Mantra and after the word SWAHA add a few grains of rice from your right hand (as little as you can hold in the pinch of your fingers will be sufficient) in the fire.
Utter the second Mantra and after the word SWAHA add a few grains of rice from the right hand in the fire.
At sunset do the same by using evening Mantras.
If you miss the timing it is not Agnihotra and you will not get the healing effect on the atmosphere or in the ash.
After each Agnihotra try to spare as many minutes as you can for meditation. You can sit at least till the fire extinguishes itself. Agnihotra creates a medicinal and healing atmosphere.
Just before the next Agnihotra collect the ash and keep it in a glass or earthen container. It can be used for plants or making folk medicines