Diwali Puja Vidhan & Laxmi Pujan

Worshipping Goddess Laxmi on Diwali has its own special significance. To say in other words, Diwali, in fact, means Laxmi pujan. But if its not done following the rituals properly, the purpose is not solved. Goddesss of Ashtasiddhi and Navavidhi, Laxmi is worshipped for attaining all kinds of material successes.
 
Why Pooja : There is special provision for worshipping Mahalaxmi and Ganesh on Diwali. When both the Sun and Moon are in Libra on the Amavasya of Karthika ( Hindi calender) Krishna Paksha, Diwali is celebrated.

Traders worship Laxmi in the day time on Diwali. On the other hand, people with families worship her in the evening, during pradosh kaal. Starting in Godhuli lagna, the prayers go on until the Mhanishith kaal. It means that while traders and others pray to Goddesss Laxmi for prosperity, priests and tantriks do so in the night.

Timing of worship : It is advised to worship the Goddess in the constant lagna. The most important thing is to have a statue which is not broken from anywhere. Based on a wooden sheet, Laxmi is placed on the right hand side of Ganesh. Place Ganesha on grass (durwa), while the Goddess should be put on a Lotus flower. Wrap the diety in a white cloth while for Laxmi use a red cloth.

Before that, place Navagraha in a plate or by purifying the soil. put sacred Ganga water, milk, curd, honey, bettlenut, coin etc. by covering them in a red piece of cloth in a bronze pot and tie it with a coconut. Put currency notes, gold or silver coins and statues or photographs of Laxmi and Ganesh Where you have made Navagraha.
Ingredients

Essential Ingredients : Keshar, Roli, Rice, Bettle, Bettlenut, fruits, flowers, sweets, sindoor, dry fruits, curd, Ganga water, incense sticks, coconut as well as a bronze pot is needed for Laxmi pujan. However, essential ingredients are peripheral only, it depends upon the financial position of the devotee.
Diwali Laxmi pujan vidhi

Devotees who wish to offer prayers to Laxmi, should firstly purify themselves and put vermillion on the foreheads. Put a red cloth on the head. Use a red woolen blanket to sit on it while performing pooja. Take sankalp and start with remembering Lord Ganesha. 

ऊँ सुमुखश्चैकदंतश्च कपिलो गजकर्णक:
लंबोदरश्च विकटो विघ्ननाशो विनायक:
धूम्रकेतुर्गणाध्यक्षो भालचंद्रो गजानन:।
वक्रतुंड महाकाय, सूर्यकोटि समप्रभ:
निर्विघ्नं कुरु मे देव सर्वकार्येषु सर्वदा।

ऊँ गजाननं भूत गणादि सेवितं
कपित्थ जंबू फल चारु भक्षणम्
उमासुतं शोक विनाशकारकं
नमामि विघ्नेश्वर याद पंकजम्।

After the Ganesha, offer orayers to Navagrahas. Take rice and flowers in your hand and then remember them-

ओम् ब्रह्मा मुरारिस्त्रिपुरान्तकारी भानु: शशि भूमिसुतो बुधश्च।
गुरुश्च शुक्र: शनिराहुकेतव: सर्वे ग्रहा: शान्तिकरा भवन्तु।।
नवग्रह देवताभ्यो नम: आहवयामी स्थापयामि नम:।

After that, worship the bronze pot -

ऊँ कलशस्य मुखे विष्णु: कंठे रुद्र: समाश्रित:
मूले त्वस्य स्थितो ब्रह्मा मध्ये मातृगणा: स्मृता: ।

It should be followed by making Swastika on a place where you keep your money and uttering the shloka-

मंगलम भगवान विष्णु, मंगलम गरुड़ध्वज:
मंगलम् पुंडरीकाक्ष: मंगलायतनो हरि: ।

Then, remember Shaiv-Parvati and other dieties. Keep Shree yantra, Kuber yantra, Kanakdhara yantra and silver coins of Laxmi-Ganesh in a plate and recall Mahalaxmi.

महालक्ष्मी नमस्तुभ्यं, नमस्तुभ्यं सुरेश्वरी
हरिप्रिये नमस्तुभ्यं, नमस्तुभ्यं दयानिधे।

Dont forget to perform Laxmi Arti after that. Then, offer prasad to the goddess and worship the diya. Make it a point to place the oil deeya on left and ghee diya on the right.