Titus 2:9-10 (ESV)
Slaves are to be submissive to their own masters in everything; they are to be well-pleasing, not argumentative,  not pilfering, but showing all good faith, so that in everything they may adorn the doctrine of God our Savior.
Slavery, It is the result of Christian influence on society that slavery has been outlawed, and condemned in most of the west. It is a taboo subject, today. Paul never did condemn slavery, though he would have condemned the abuses with which it was associated in the American South. It is embarrassing to think that many of these slave owners considered themselves “Christian” while treating fellow brothers and sisters in such shameful manner. Paul here though talks about how slaves should behave in their predicament. Slaves were in a position to show their owners the blessings of Christ in a unique way. They were to distinguish themselves from other slaves by not being argumentative, and not pilfering (stealing, from their masters) but being faithful to their masters. In doing this they would undoubtedly improve their lot, through legal means.
The same can be said of employees today. Doing your job faithfully, not arguing with the boss, and not pilfering is a common sense way of getting ahead in life.