NOTE: This page is currently obsolete due to Stick Empires giving everyone free membership in an update.
Make a PayPal account which you will use for paying for membership with your free money
If you are under 18 you will need parental assistance to create an account.
Step one is find a means to get money without having to get a job. There are many ways you can do this such as completing online surveys through a business in exchange for money into a PayPal account paid by the other business conducting the survey or other tasks such as online data entry. While there may be a lot of scams when you search for this there are also legitimate companies too.
Get started: http://lmgtfy.com/?q=surveys+for+money
Be aware that many companies will have minimum age requirements, which can vary from 18 to 16 or possibly even lower though you'll find it harder to find companies willing to work with under 16 year olds.
With your found company offering money into your PayPal on completion of surveys all you have left to do is sit back, check your emails every now and then, and complete the surveys (don't lie) to get the money.
Now that you have money in your PayPal account just log onto Stick Empires as normal and follow through the purchasing steps. If you've earned more than $4 per month you'll have left over money you can use on something else for as well!