I recently went through this process after I was unhappy with my own pan. Here are the steps you should follow:

Put the pan in the oven self-clean cycle to strip it. Some people say it's harsh on the pan. It probably is. But one time should be fine. I'd rather do that than mess with soaking it in chemicals and the black sludge that results. Mine came out perfect. Make sure you clean with soap and water afterwards.

Preheat your oven to 250 F. Put your pan in for 10 minutes or so. The idea is just to get it warm, dry any water, and open the pores.

Remove from oven. Increase oven temp to 300 F while you do the next part. Rub all over with your oil of choice. I've always used canola.

Now, immediately remove the oil with a dry rag or towel. Use multiple rags if you have to. You're removing any oil on the surface. The pan will retain a thin layer of oil within the pores you opened up in the previous step. Why do you want to do this? Having excess oil on it will not polymerize properly (more on this below) and create gummy spots.

Put the pan back in the oven, face down. Bake for 15 minutes. Remove from oven. You'll notice that the oil has created somewhat of a pattern on your pan. Use another dry towel to wipe that out. This way you'll get an even, black finish.

Increase to 400 F and bake, face down, for 1-2 hours. Your oven may smoke a bit. This is not only ok, but good. The goal is to create a layer of polymerized oil, which turns it essentially to a plastic, which gives it the non-stick properties. You have to exceed the smoke point for this to happen (however, in the future you do not want to cook above the smoke point, because that breaks down the oil and gives it a bad flavor).

You can do this once or twice, and have a good base. But how do you maintain? Easy. Very similar.

Cook with it. When done (and cool) put it in the sink. Use soap and warm water to scrub it out (remember it's a plastic, so soap won't strip your seasoning). Turn on a stove burner to med-high. Put your pan face down on it. Allow it to heat up. Why face down? It traps the heat in there, allowing the entire pan to heat up somewhat evenly. If you put it down normally, the center of the pan directly under the burner receives most of the heat.

When pan has fully dried and is warm, apply oil. Then, wipe it off again (you've heard this before, right?). Return to burner, face down. Heat for 5-10 minutes. lift it up to check for smoke every so often. Once it's smoking, turn off the heat. Allow to cool, wipe, and put away.

Sources: I largely followed this Youtube video for my initial seasoning.

Here is an article on polymerization and smoke points.