Avoid trouble during high school

In high school, you can get into trouble in ways that could radically alter your future life trajectory in ways that are (for the most part) bad. Examples:

Drugs, alcohol, or smoking, both the activities themselves, and getting caught doing them.
Getting pregnant, as well as other problems related to sexual activity, such as getting in trouble with your school for sexual activity, getting a sexually transmitted disease, etc.
Getting a police record due to violent or property crime or gang activity.

As a general rule, we recommend avoiding these while in high school. A couple additional points:

Some of these activities are not unsafe or undesirable in principle but they can be started later. Delaying parenthood (and sexual activity) to after high school is better both biologically and socio-economically. Moderate alcohol consumption is claimed to have health benefits, but that too can be begun later.
In some cases, it is not the activity itself but the implicit social context and the maturity level of the other people around you that makes it dangerous. The examples of drugs, sex, and alcohol are particularly noteworthy.
While it may be the case that some people are unwilling to be friends with you if you don't engage in these activities, you should weigh this downside based on the probability (generally low) that you'll need to rely on their friendship or being part of their social circle over the long term. There may be ways of navigating these issues while minimizing social friction.

The good news is that avoiding trouble of the above sorts is generally easy if you put your mind to it -- the hard part is just deciding to avoid them.

Some people gravitate toward trouble because the day-to-day academics and school activities feel boring, and they do not have an outlet for their creativity and sense of adventure. if that describes you, then look below at the section The positive.

There are also somewhat more mild forms of getting into trouble, that do not leave a permanent black mark, but can still be a big liability in the short term. These generally center around relationships with your teachers and fellow students and your academic performance in specific subjects.