Texas Government Code Chapter 411, Subchapter H sets out the eligibility criteria that must be met. Applicants must be at least 21 years of age (unless active duty military) and must meet Federal qualifications to purchase a handgun. A number of factors may make individuals ineligible to obtain a license, such as: felony convictions, some misdemeanor convictions, including charges that resulted in probation or deferred adjudication; certain pending criminal charges; chemical or alcohol dependency; certain types of psychological diagnoses, and protective or restraining orders. The state eligibility requirements can be found in GC §411.172. The federal firearms disqualifiers can be found in 18 USC 44 §922.
You must also submit a completed application, pay the required fees, complete all required training and submit required supplemental forms and materials.