What meditation technique can one practice if one does not have access to a master or guru in order to be initiated (would it still be effective, or without a master’s initiation, the technique would not work)?

Simply sit quietly and concentrate on the center of concentration until the perceived concentrator dissolves in the concentration itself. Aware of the Presence which is felt when thoughts are allowed to come and go without undue attention being given. This Presence is the Guru that will initiate you into Your Self deepening and instructing you from within. All else is in the field of concepts and illusion.

What follows after enlightenment, what is there left to achieve?

Enlightenment is the dissolution of the false idea of separation brought about by the ‘I am a body’ idea. Once you have identified yourself perfectly, without the body,  your actions are spontaneous. Discarding illusion in each moment as it arises is the only thing “left”, and is the Greatest achievement You can perform using a human body.

How do you bring yourself into the present moment?

Stop imagining past and future using the instrument of mind.

What are your views on meditation? Do you find it effective?

Meditation allows you to observe the flow of thoughts, seeing that they can pass by without an action needing to be taken. As you become aware of the mechanism of the thought process, you discover yourself to be outside of it, there by no longer are you a slave to thinking thoughts.

What is enlightenment and how it can be achieved?

“Enlightenment” is merely the Realization that You are not the body which spontaneously dissolves the false concept of separation. Physical, Mental, Emotional, Relations etc. all have to due with the body that You are not. As this Realization deepens the pressure of body knowledge dissolves or disappears and is easily discerned from Your Presence That You Are. From the perspective of the mind body, this will feel like an expansion, in Reality it is merely dissolving the illusory layers appearing on Your Presence.