The common materials needed for performing Tharpanam include:

• Mat or Asana: To sit on, preferably made of sacred Darbha grass (Kusha grass), a wooden plank, or a clean cloth of natural fibers.
• Plate: Made of wood, copper, brass, or silver to place the offerings. Avoid glass and stainless steel.
• Water: Clean water in a copper, brass, or silver cup for offering. You may also need extra water in a bowl.
• Black Sesame Seeds (Til): Considered sacred for ancestral rituals.
• Darbha Grass (Kusha Grass): Several strands are needed. A ring made of Darbha grass (Pavitram) is also worn on the ring finger of the right hand.
• Raw Rice or White Rice Flour: May be mixed with sesame seeds for the offering.
• Coin: A small coin (dime or nickel), or a gold coin if available, to be included in the offering. This can usually be reused after rinsing.
• Sandalwood Powder: May be used to make a paste.
• Flowers or Petals: For offering.

Optional:

• Pindas: Rice balls, traditionally used in some regions.
• Ghee: Clarified butter.
• Lamp and Incense: To create a serene atmosphere.
• Ganga Jal: Holy water for purification.

• Paternal Lineage:Father (Pithru)
  Grandfather (Pithamaha)
  Great-Grandfather (Prapithamaha)
  Their respective wives (Mother, Grandmother, Great-Grandmother - Matha, Pithamahi, Prapithamahi)
  
• Maternal Lineage:Maternal Grandfather (Mathamaha)
  Maternal Great-Grandfather (Mathuhu-Pithamaha)
  Maternal Great-Great-Grandfather (Mathuhu-Prapithamaha)
  Their respective wives (Maternal Grandmother, etc.)
  

If any of these ancestors are still living, they are not included in the Tharpanam. In some traditions, if an ancestor in the direct line is alive, you may extend to the next preceding generation.

Some traditions also include offerings to other relatives like uncles, aunts, siblings who have passed away. Additionally, "Karunya Tharpanam" might be performed for all departed beings, including plants and animals that have sustained us.

If you are going to perform Tharpanam after a long gap, the procedure remains essentially the same.

However, you may want to:

• Re-establish the Connection: Mentally reconnect with your ancestors with sincerity and devotion. The intention and heartfelt offering are crucial.
• No Specific "Missed" Rituals: There isn't usually a specific compensatory ritual for the missed Tharpanams. Just resume the practice with faith.
• Consult Elders or Priests (Optional): If you feel particularly concerned or have specific doubts due to the long gap, you can consult knowledgeable elders in your family or a priest who can provide guidance based on your family traditions.
• Regularize the Practice: Aim to perform Tharpanam regularly on Amavasya days going forward to maintain the connection with your ancestors and receive their continued blessings.
• Focus on Sincerity: Whether it's after a long gap or a regular practice, perform the Tharpanam with sincerity, respect, and faith. The attitude and devotion are more important than just the ritualistic actions.