Need beginner tips to start my story.

Hey guys! So I have an plan to start writing this little idea and I would very much appreciate some reviews of what you think and advice please and thank you!

Ok here's a plot summary of the story I came up with (I wiil show where I need advice later). Ok so the story revolves around a slave, he has been a slave his whole life in fact you could say he was born into it. Although his master has made him believe that he was rescued as a child and as such feels that he owes everything to his master and has an un-dying loyalty to his master, his love for his master clouds his judgement and blinds him from the truths of the world. He is not a regular slave but rather the masters personal and best bodyguard.Raised and taught to fight, he protects his master with every ounce of his being and would gladly lay down his life for his masters. His master however did not rescue him and keeps the truth hidden away from the slave, only for the truth of what happened to his family to be revelead later... The master has a son the same age as the slave and they would often play togehter and train together. They see each other as brothers and the slave sees his master as a father figure, although the master never sees him as a son but a belonging he cares much about... The master has a seems kind but would sell his own wife for the right price and hates to mix business with personal feelings. The slave grows older and falls in love with one of the slave girls. Together they have a child, but the master sees this as a opputunity and sells them both. This is where the slave snaps as feels he has been betrayed by his own "father" and has to chose between the loyalty he has for his master and the love of his family... Ok so here's where I need help, I have two settings for this story. One. It is set in past times where slavery is not an uncommon thing however this is loosely based on actual events as the end of my story will protray the end of slavery where in actual historic facts will not happen that way. Two. It is set in the distant future, earth is destroyed and the remaining humans travel to a distant planet inhabitated by an alien civilasation that is still going through the "slavery phase" if I do option two I could depict more technological things and the master and his family would be aliens ofcourse and the slaves human as the aliens see the humans for a chance for free labour. So I need advice on which to chose and why. So I've told you alil about my idea like a basic summary so please! Feel free to leave your thoughts and ill review one of your things to. Any other advice or tips you would like to pass along to a new writer please feel free.

Author's Note

Please ignore grammar I'm working on it XD.