Machine Tower
To simplify the explanation just a little, I have incorporated a map system.

This is a map of the next section. The path to the boss is marked in yellow. Follow that path if you want to just beat the boss. To get all of the extra items along the way, take the lavender path. The gray areas are hidden rooms. You must strike the wall with your whip to access them. The red dots are Heart Max upgrades. The orange items are Health Max upgrades. The light blue items are Magic Max upgrades. You can only get the upgrades that have lavender lines going to them. The other ones you will need more Magic Items to get to. The red squares are save points. Always save your game at a save point. Not only can you save your game but you can also replenish 100% of your health and magic. Be aware that I will not tell you to level up. It will be your responsibility to do so. I will also not remind you to go back and grab any extra items that you may have missed. You can stray from this guide at any time to get extra items you missed.

Follow the yellow line until you get to the Machine Tower. Now, Save at the save room and grab the three extra items in this room. Now, head to the next room. In here is one extra item. Grab it then follow the lavender line to get two more in another room. Now, return back to the yellow line and head to the next room. In here is one extra item. Grab it and follow the lavender line left to get another. Head back to the yellow line and continue on to the next room. Save your game and head to the next room. Grab the extra item in here and head over to the boss room. Crush the boss and then head to the next room to get the Kick Boots. Now head back to the save point. Save your game and head right to the next room. In this big room, take the upper-rightmost door to the Audience Room.