What least basic thing can someone do to start his spiritual journey?

The most basic thing one ought to do to start his spiritual journey is...
Get the knowledge of two fundamental things:
who am I and
who is governing this world (who is the doer)?
Once we get this knowledge, it solves all our worldly problems and we get free from all unhappiness.
Spirituality provides a permanent solution to all problems.

In this world there are so many religions. Religious rituals and practices help the development of every person. But ultimately when we get Self-Realization, we attain the ultimate knowledge which gets us started on our spiritual journey. And this very knowledge makes us reach our final destination of salvation.

When we realize ‘who am I’, it is called Self-Realization
We say, “I am John (you may insert your own name here).” But we are really a Pure Soul.
Pure Soul is the right and permanent answer of ‘who am I’.

‘I am John’ is relatively correct. But ‘I am permanently a Pure Soul.’ is really correct.
Now, how do we know what is a Pure Soul, what are the properties of the Pure Soul, how is it separate from the thoughts, speech and actions.

We get this knowledge very easily and effortlessly through Akram Vignanr
This is the knowledge of the Self.
In religion, we have to do worship or penance or have to leave our husband or wife, our home, all money, property, etc. and do meditation in order to develop ourselves so that we can reach the stage of attaining Self-Realization.

However, the Akram path is a direct or a stepless path to Self-Realization. Here, we directly realize our Self by the grace of Gnani, the Enlightened One, in two hours only.

Only when we know who am I and who is the doer, can our spiritual progress startr
Religion teaches us to leave bad things and adopt good things. But on the spiritual journey, we don’t indulge in leaving or adopting bad or good things; we directly know who am I and who is doing the good and bad things. In other words, ‘I, as a Pure Soul, remain the knower of the doer.’

When we are not the doer of good things, nor a doer of the bad things, then the charging of new karma cannot take place. It means no more new bondage can come onto us now. This is what leads us to ultimate salvation.
Thereafter, all we need is to be in touch with Gnani and follow his given words.

Just like we enter in medical college, here, on attaining Self-Realization through Akram Vignan, we are entering the spiritual college of liberation. So, we need to attend at least 300 hours per year with Gnani, who through his valuable teachings shows us the way forward.
We need to be in touch with Gnani because it is given knowledge. Confusion could arise in our mind owing to so many prior beliefs that we may be having, on account of whatever we have been doing so far in our life to procure liberation, as we want salvation.

Gnani, very compassionately, explains, “Whatever you are doing with doership, it won’t help you reach to the realization of Pure Soul. You can be in satsang in touch with us. You ask, ‘whatever I am doing is correct or wrong? what is correct?’ So we’ll explain you. The wrong belief will get fractured, and right understanding, more and more clear understanding, you shall get from this satsang. Then only, you will get more and more experience of Pure Soul.

So first, understanding should be clear, then the awareness, and then the experience of Pure Soul - these are the steps. When you remain in touch with us, you will get step-by-step awareness and further experience of Pure Soul exactly. That’s why we always prefer that you should remain in satsang in touch with us.”
To conclude,
When one attains Self-Realization, the worldly development completes there; new karmas stop being charged then. Thereafter, remaining in satsang of Gnani and following his instructions, when even the discharge of old karmas will finish, one attains final liberation!

To know more: https://www.dadabhagwan.org/self-realization/