There are many type of slaves in history. War slave, people from the losing side of battles. Debt slave, people who cant pay their debt and are forced into slavery to pay the said debt. Criminal slave, people who committed crimes that punishment for them is slavery. There are also random people who get kidnapped by bandit or syndicate to be sold as one type slave above even though they are originally are free people because hey bandit need money and their existence never shy from crime and dubious practice. I forget the name but there's also one type of slave for some amount of time with a contract until they can pay the price of their freedom. Slavery is bad, I know it. I also feel sympathy for people who have the misfortune to live like that, hell I even don't want to be a slave. But as ruler I should consider everything, thinking twice, no thrice before giving an order and proclamation. Do wrong move and people might revolted against me with my head severed by guillotine. Unless I can give them a better alternative because even in our history people use slave to do labor, , they have huge fields of farms but little of hands so they use slaves. It was until the technology revolution that no more people need to do much labor because there are machine to do jobs much better that than humans. Until there's a better alternative, on this I might follow @Ai chan suggestion as well to push the kingdom to science and educated the masses. To be a ruler is hard and tough job and I never want to get job like that, they lead a whole nation where every decision they make will have consequent to a lot of population and some people will hate them because no matter the choice it's hard to please everybody.
Slavery is the product of a society system, if society is based on war, killing the defeated is a waste of resources, so slaving is the best use of it or a more modern one which one person is more worthy "free" spending and getting into debit. There is the system of using prisoners as work force too, but it's more for a centralized government.
Tax the slave traders, the slave sellers, and the slave owners so high, it'd be cheaper to hire servants.
SJWs are triggered by this thread. Were it me, I would make it so that slavery gets abolished in all forms!
I'd first try to control the power of Nobility and whatever Merchants first so they wont cause trouble when I do free the slaves. That is, if I don't die first since I probably won't be a good national leader due to no experience.
Slave abolishment had to do with more than just the factor of nobility or rich.. It had to do with the world becoming more and more accessible, education was becoming norm, people were becoming aware of life outside of their churches or houses, machines were getting invented that required fewer manpower, there was just this global drive to evolve beyond just survive, to flourish. It was an inevitable event. If I was a ruler at a time when slavery was what drove the trade industry I'd just be drowned by the world if I went against it (ex-Egyptian time) . There must be enough alternatives to fill the gap it creates.