Hazrat Moulana Ashraf Ali Thanwi (rahmatullahi ‘alaih) once mentioned the following:
If a person firmly holds on to three things, then even though he may not become the Junaid Baghdadi of his time, insha-Allah he will not be deprived (of acquiring the goodness of Deen).
The first thing is that one should completely abstain from all types of sins. The reason is that through committing sins, a type of darkness is created in the heart. Hence, even if the sinner thereafter engages in ‘ibaadah, the noor that he will acquire through the ‘ibaadah will be like the light of a lantern that is covered with a net on account of the light being mixed with the darkness (of sin which has covered the heart i.e. until one does not make sincere taubah, the effects of the sin committed will remain on the heart).
The second thing is that one should not entertain evil thoughts regarding the creation of Allah Ta‘ala, as this (entertaining evil thoughts regarding any person is a sin which) stems from pride.
The third thing is that whenever one finds the opportunity, then to the extent that one can manage, one should engage in zikr and other ‘ibaadaat. Furthermore, one should also spend time in the company of the Sufiyaa-e-Kiraam (the pious servants of Allah Ta‘ala).
(Malfoozaat Hakeemul Ummat 13/54)