Substance Use Management
Since there will always be risks involved with using drugs, reduce harm by controlling the quantity. Maybe use the substance less frequently or lower your dosage.
You can also set goals for yourself, such as you won't use the drug during the week or only once a month. You can lengthen the time between usage to reduce the harm even further and lower your tolerance.
Consider buying less of the substance when you do want to use it. If you buy less, then you will have less available to consume.
Take Care of Yourself
Finally, you need to ensure that you are taking care of yourself while using drugs. Taking care of yourself might mean staying hydrated, not driving when using, and making sure you are in a safe space.
Using drugs is a choice you may make at some point. It's up to you to find ways to reduce harm to yourself and others if you do.