According to the four noble truths, suffering is an inherent part of existence, the source of suffering is ignorance, the main symptoms of ignorance are attached and craving and that this can ceased and lastly the noble eightfold path will cease the attachment and suffering.
Wisdom cannot be achieved through following an enlightened one; this is evident from the book where Siddhartha and his friend part in search for enlightment, it cannot be achieved through words and teachings and the reason is because they may talk the truth but being concepts they trap you.
To reach Nirvana one has to destroy the self in order to attain knowledge of the unknown innermost. When one reaches this state you experience peace and you lack desire and passion, this is illustrated in the book where the enlightened one is described as "Every finger of his hand spoke of peace, spoke of completeness, sought nothing, imitated nothing, reflected a continuous quiet, an unfading light, an invulnerable peace".
To be wise you have to love the world and other people not because of their teaching but because of their deeds and their life, this is also in the book where Siddhartha explains to his friend that "It is only important to love the world, not to despise it, not for us to hate each other, but to be bale to regard the world and ourselves and all being with love, admiration and respect".
(Hermann (1971) Siddhartha page 147)
Above all you must learn to listen with a still heart, without passion, without desire and without judgment, you must listen with a waiting and an open soul, in the book Siddhartha learnt to listen from the river where he spent most of the time listening, this is also evident in the noble eightfold path where in order to achieve nirvana one has to have the right concentration. "Siddhartha learnt from the river how to listen, listen with a still heart, with a waiting, open soul, without passion, without desire, without judgment and without opinion".
(Hermann (1971) Siddhartha page 106)
To be wise you have to learn how to make sacrifices, Siddhartha learnt how to pray, fast and to think, this he got from the teachings of samana, and you must have self control and must not be destructed by earthly desires, for they will mislead you to what you are looking for. Siddhartha is a good example to illustrate this, he went to the city and forgot how to pray, think and fast. The world gave him much experience but did not give him the answer.
Wisdom can be achieved only to those who sort it, it cannot be achieved through words and it needs action, Siddhartha left his home in search for knowledge, if he had not left home he wouldn't have reached nirvana. You must be ready to make sacrifices and not be led by desires, Siddhartha left his lover, wealth and the city to go live with the ferry man, this shows a lot of sacrifice and this is what one deserves to do in order to be wise.
The decisions one makes must be right decisions, you should evaluate the options of anything that you do before