It depends on where you work, if you have a partner or are trying to raise a family alone, and what your standard of living is. Police officers tend to work side jobs, not because they have to, but because they want some of the nicer things in life.
There is a big difference between a game warden and a park ranger. I encourage you to look into this in more detail. I know Texas game wardens are paid well. Not so sure about the park rangers. However, there are also park rangers in the Nat'l Park Service. They are federal employees.
Money management is essential. Controlling "Wants" is important. If you "need" a super-nice car for status, when all you really need is reliable transportation, money will be tight. The more you can learn about handling money before going out on your own, the better you will be!
If you are passionate about being a Game Warden or Park Ranger, then you follow your passion. If wanting to seek more of a financial reward for supporting your family, find out what growth within the fields are available and would allow for meeting your needs. I'd just agree with all Kim mentioned, as well. First learn the differences in these jobs, which a few older Game Warden friends here in Texas are more than capable of supporting their family while performing the duties of a Texas Criminal Justice officers. Park Rangers, even though their starting salaries are somewhat less than those of a Game Warden, would still have similar risk within this career in upholding law enforcement duties. Parks and Wildlife along with the Criminal Justice research may help you in determining if this passion for this field is something you really want to do, or possible can still find other careers outside of this field that would better fit your future needs, but still be able to be outdoors. *Salary and Growth info near the bottom of each of these links, which could help in you seeking this type of career path.