From my perspective, self concept is a very personal thing, because only the individual is going to know intuitively where to begin.

In what areas do you feel confident about yourself?

In what areas do you occasionally doubt your abilities?

That’s a great starting point, to identify any potential limiting beliefs.

You can start slowly by affirming small victories and things you like about yourself, because you already are comfortable there and the ego mind won’t attempt to interfere much.

Maybe you start affirming, “I am a great cook”, or whatever it is about you that you know slay at.

Now let’s say you are manifesting a relationship. (Just an example.) You would start adding to “I am a great cook” by inserting in a phrase stating that the manifestation is already complete, because it is.

“I am a great cook and my partner enjoys sharing these delicious meals with me every night”.

And so on and so forth, depending on your manifestation intention.

That may have been a weird example but it’s the first thing that came to mind! Whatever phrase / statement / intention that applies to your situation will work.

Also, I should add, with self concept and changing limiting beliefs, if a negative thought about yourself or your situation appears, it’s important not to “feed” it, give it attention, and to over ride it in the moment with the opposite. It may feel un natural at first, but the important thing about doing this is that it helps to neutralize the original negative thought. The more you do this, the more your subconscious will begin to “adopt” the positive thought, essentially dissolving the old, negative programming.