Learn as much as possible from other organizations, and try to rise to upper management. Being at the clerk level is increasingly less rewarding as you grow older. In terms of job security, go for a Federal or State employer: Better benefits and job security will be your rewards. Also, public sector has great retirement payouts.
Essentially, it's dull, dull, dull work. So have fun with your co-workers and always welcome new and better ways to handle problems and duties.
When the U.S. Constitution was written, the federal government was not allowed to collect income tax. All revenues came from trade tariffs. The 16th Ammendment later permitted federal income tax.