Where can we get the best guidance to become better Muslims?

There are many things Prophet Muhammad (ﷺ) told us. This is why when he used to give a talk, he had a special opening speech which is called Khutbah Al-Hajjah. At the end of it, he would say, “The most truthful of speech is the book of Allah. Then the best form of guidance is guidance of Muhammad.” [1]

His (ﷺ) guidance is the best. So if we want to be better Muslims, if we want to enter paradise, then we have to go back to his guidance and what he provided us with. This is what he talked about, for us to improve ourselves. We have to treat this life like we are strangers, travelers. Abdullah Ibn Umar said, "Allah's Messenger (ﷺ) took hold of my shoulder and said, ‘Be in this world as if you were a stranger or a traveller.’" [2]

We need to do whatever we know is necessary, what will remain with us in the afterlife, what will benefit us later on and what righteous deeds are. We have to make great effort to do righteous deeds, and we should only take from this life, which is absolutely necessary for our survival; we should try not to accumulate what we do not need. These are all part of the guidance of Prophet Muhammad (ﷺ).

References: 

[1] Sahih Bukhari, 8:73:120

[2] Sahih Bukhari, 8:76:425