I think the superior way is to use the Automation Object Model (AOM) which is the ActiveX rich automation interface provided by QTP. There is a separate manual on AOM in QTP 8.2, and a large chapter on online help for QTP 9.x. You can also search this forum this forum for either "AOM" or "Automation Object Model" for many threads that talk about this.
Finally, you could use a QTP script itself to run two or more other scripts. Here is a thread on this topic. From the forum's FAQs:
Even though I wrote the above article, I think that using AOM is the better approach.
In either of the above approaches your tests can and probably should support Test Parameters, which thereby allow the script caller to set one or more input parms to configure the test. Search the forum for that phrase to learn more.