What should I do to become righteous and rid myself of recurring sins, such as smoking and drug abuse, especially after breaking numerous oaths? Should I become strict in obedience and repent every time I fall into sin, or should I persist in sins until I expiate all my oaths and then repent?

Repentance from all sins is immediately obligatory. If one repents from a sin without repenting from another, their repentance for that specific sin is valid, and they must hasten to repent from the sins they are still committing. Repentance from all sins must be immediate, without any delay, while seeking Allah's help, making abundant supplications, resorting to Him, associating with the righteous, and performing supererogatory acts of worship and obedience, for good deeds efface evil deeds. If you return to sin, repeat your repentance and do not despair, and strive for steadfastness. Do not delay repentance; rather, hasten to expiate your oaths while also hastening to repent. If you return to the sin, repent and do not despair of Allah's mercy.