You have no compulson for any refrain while your Yagya is going on as the Pandits do all what you personally need to do but following these may increase the results of Yagya:

• Prayers, Keeping Fast, Visiting Temple, Church, Mosque etc.
  
• Take bath in the morning before you eat.
  
• Keep yourself clean, pure and fresh (Mensuration excempted)
• Do at least 5 minutes meditation in a day
  
• Being vegetarian in this period is not necessary but is a plus. 
• Try to concentrate at least 3 times a day for what a Yagya is going on. If your Yagya is for money then you should at least 5 minutes stand with photo of your God/s and pray for that. Again you should analyse at least 5 minutes daily at the same time why money doesn't come, what you should do for this. This accelerates your Yagya towards your purposes.
  

• Don't lie, don't curse someone, don't beat / hit someone
  
• Do not steal, do remain honest in this time even while buying vegetable. (Remember, when you bargain, you lie too)
  
• Do not drink liquors heavily
• Avoid fast and risky driving
  
• Avoid fight, screaming and violence.
  
• Don't sleep over the day, after sunrise and before sunset.
  
• Do not let your trust fall from God. Your trust works centrally in Yagya.