40 day practice

The period of 40 days has been widely recognized as an auspicious period both in the East and the West since ancient times. A traditional way to do an extended practice of Om Namah Shivaya mantra is to choose a number of repetitions for 40 days. The mind likes to have a beginning and end to a practice, a sense of completion, such as comes with a 40 day (or longer) practice.
Fixed time per practice session: The mind finds comfort in knowing that it will do the practice of one round of 108 repetitions (or some other number of rounds), and each round will take a predictable amount of time.

Same number of rounds: The mind likes the predictability of doing a certain number of rounds per day. The mind may resist at times, but once it gets started in practice, the mind likes the habit.

Specific number of days: The mind also likes the plan of knowing how many days or months practice will take to complete. This can be very beneficial in stabilizing a noisy mind, which is a common complaint.

A mala is a set of counting beads with 108 beads. Only 100 are counted, with the other 8 considered an offering to the divine, however, you personally hold that. You might choose to do 1, 2, 3, 4, or more rounds of 108 mantras per day, counting with a set of mala beads.

It has been said that there is freedom in discipline; choosing to do a regular practice frees the mind from wondering what practice will be done that day. It is also important not to do the mantra practice with rote repetition, but rather, with feeling and awareness.
By running your own experiment for 40 days, you can decide for yourself whether or not the practice of Om Namah Shivaya mantra is beneficial.

Extended practice

A noticeable level of mantra siddhi (power of the mantra) is said to come with 125,000 repetitions of a mantra (Such an extended practice is called a purascharna). This is equivalent to 1250 rounds of a mala.

Such an extended practice with Om Namah Shivaya mantra can have a tremendous effect on stabilizing the mind in preparation for advancing in meditation. Such a practice simply must be done personally to understand the benefits. It does take quite a commitment to do this practice every day for such a long period, but it is well worth the effort.

In choosing the level of practice per day, it is important to have stability from one day to the next and to not skip any days. It is best to choose the level that works for you consistently, rather than changing the number from day to day. For example, if two rounds per day is a good number, then it's better to stay with that amount each and every day, not to do none on one day, but four on the next day.

How To Keep Shivlinga at Home: Direction of Placement of Shiva Linga

As per Agama Shastra, there are two acceptable orientations of the Shiva Linga.

1. The Yoni base faces the north, and the devotee faces the east (towards the West face of the Lingam).

2. The Yoni base faces the east, and the devotee faces the North (towards the South face of the Lingam). The Yoni base here shall mean the point from where the Abhishek liquid (Water or Panchamrit) flows out of Shiva Ling.