This is nothing you have to plan, if you are going to Marrakesh, you will for sure spend some time just wandering around without any idea where you are. The Medina of Marrakesh (old town) is basically just random streets build as a labyrinth, filled with a lot of marketplaces and shops (also called Souks).
I did not think that the sellers were too pushy, but the prices might be a bit more than you actually expect, so it is important you show your best negotiating skills if you feel like buying something. Before buying anything, decide how much you are ready to pay for it, and tell the seller half price, then you will more or less get close to the price that you are ready to pay. Some of the sellers might get offended, but I mean some of them also tell stupidly high prices. I ended up buying some plates, shoes, pants and also getting a henna tattoo that they do all over the Medina.
You should also have a drink on a rooftop within the medina (there is plenty), both during the day time and night time. Specially on the night it is nice to watch the buzzing market place Jemaa el Fna fom a rooftop. Getting into the madness in the night is not maybe something I highly recommend, but it was for sure an experience worth remembering. I felt like punching them all in the face to be honest, although I actually wanted to eat in that market place during the night. They are very, read: VERY aggressive during the night in the food market if you get in the middle like we did.