Once you have selected an initial topic, the next step is to develop research questions. Do this by using probing questions. Phrasing your topic in the form of questions helps direct the research process.
WHAT questions focus on a particular aspect of the topic.
WHY questions ask for an explanation of something--why it happened, why it did not happen, or why one thing is better than another.
WHEN questions focus on timing or history.
WHERE questions focus the topic on a location, either geographical or other.
HOW questions focus aspects of the topic on a process or on the origin.
WOULD / COULD questions focus on possibilities.
SHOULD questions focus on the appropriateness of a particular action, policy, procedure, or decision.
Source: Mike Palmquest. Bedford Researcher. Colorado State University.
A good research question will lead to your thesis statement.
For example, the question...
Are there any psychological, social, developmental or physical impacts on children who've played with gender-specific toys?
...might lead to the following thesis:
Gender-specific toys impact childrens' lives in many ways: They impact how children view themselves, the skills that they learn, how their brains develop, and their social skills.
Strong thesis statements
or "why should I care?" test
Source: Thesis Statements. George Mason University.
Image source: Powernowllc. CC0 1.0. Wikimedia Commons.