Repeating a Mantra with or without a counting device is known as Japa. To control the mind, aspirants of all religious – Jews, Christians, Hindus, Muslims, Zoroastrians use as a powerful tool . They believe that an idle mind is the devil’s workshop and by doing prayers or japa with a rosary or japa mala they accomplish practical work on themselves. To make its effects more positive, durable and powerful, japa is used with some additional tools

No fire worship needed, When Japa is done without any desire.

Japa can be done with

a mantra (with or without Aum at the beginning and end)</li>
the name of a diety
bijas or bija mantras
Aloud
Silently

Silent Japa, Known as Upanshu Japa is supposed to be more powerful than japa said aloud. An easy way to exercise silent japa is to perform japa aloud for a period of time and decrease volume of the sound and gradually start doing it silently.
strong Using a Mala for Japa strong
In doing  with a mala, one should observe the following guidelines

Mala should be used by the right hand.
The Index finger and the little finger should not touch the beads
Beads should be held by the middle finger and ring finger and should be turned with the help of the thumb
There is always an extra bead hanging outside the row of beads, whose total number is usually 108, This 109th bead is called Sumeru
Aspirant should start the Japa mala at the first bead next to sumeru and should end on the last bead before sumeru
If the aspirant has to Japa mala twice he should turn mala and make the last bead (the one which he ended his first round of mala) become the first bead for starting the second round of the mala
Type of Mala beads
Mala, the counting device for japa, is generally made of 108 beads. The material that the beads are made of has an effect on the body chemistry.

Possible material include

Tulsi wood
Sandalwood
Lotus Seeds
Rudraksha

Coral
Pearl
Crystal or Sphatik

Small malas, called sumirni are made of fewer beads, although the number is divisible into 108. For example a sumirni is made of 27 beads. 108 repetitious of a mantra completes sumirni four times. A malas can be made of 54 beads in which case two malas make one japa or 108 repetitions.

Tulsi mala is best for believer s of Lord Vishnu, Ram, Krishna or hanuman

“https://rudrapuja.com/product-category/rosaries/rudraksha-mala-rosaries-and-bracelets

Rudraksha mala is for believers in Lord Shiva and Shakti

“https://rudrapuja.com/product/sandalwood-mala-high-quality-8mm/”

Sandalwood mala is common

For Shanti Karma, pearl mala or coral mala is very effective. Coral mala is good for worship and japa done to attain wealth

Rudraksha is supposed to be most beneficial Japa mala and even better than a mala made for Silver, gold, coral or pearls. The rudraksha should be neither very small nor very big.
How to Use Japa mala
Besides being a counting device, a mala is a good centering device. Engagement of the fingertips is engagement of consciousness. Mala practice creates a habitual centered state of consciousness.

A mala japa very frequently gets charged with energy after it has been used for. If one has done 125000 japa one mala, that mala itself becomes a Siddha (charged with energy) and gets energy by wearing it, also the mala conditions the brain so that each time you see it, reminds you of your mantra.

For starting a new japa, a new mala should be used, however if the mantra remains the same, the same mala can be used for generations.