I'm fairly new to traditional archery but, I've been a cast iron man my whole life. You're right, new cast iron is rough on the cooking surface and is not very conducive to non-stick cooking. At least not right away. And the factory pre-seasoning, as others have posted, is a joke.
Here is the method I use with great success every time I get another piece of cast iron cookware. I have over a dozen, mostly old Griwolds, Wagners, and no names but, I also have a few newer, Lodge type skillets and a three leg dutch oven.
You'll need some Dawn or similar dish washing detergent, a pound or two of very fatty bacon, a metal, flat edged spatula with slightly rounded corners and a few paper towels.
The first thing I suggest is wash your skillet with very hot, very soapy water and a brillo pad. I know this goes against the grain but, I personally don't trust the methods or materials used to preseason at the factory and you only need to do this one time.
Next, begin seasoning your skillet the right way. Make sure you fully preheat (fairly low heat)the skillet before use. Check to see that the skillet is fully preheated by carefully checking the rim with your hand. A quick tap will let you know the skillet has heated all the way through.
Next, fry the bacon maintaining fairly low heat. Be sure you don't use too much heat and cover while frying because you're not going to drain the grease. If your heat is too high and you don't cover the skillet, you'll have a splattering mess by the time all the bacon is done.
As you cook the bacon, you'll notice some darker material is sticking to the bottom of the skillet. Use the flat edge of your spatula to gently scrape the offending bacon remnants from the skillet. Be sure not to gouge the cooking surface.
Once the bacon is fully cooked and removed from the skillet, turn off heat but, leave the skillet on the burner. Take a wadded up paper towel and carefully dip a portion into the hot bacon grease. Make sure you keep track of your fingers! Now, using the grease laden paper towel, rub a light coat of the bacon drippings all over the skillet excluding the bottom. Coat the inside, rim, outside and handle with the grease and allow to slowly cool on the burner with the bacon grease still inside. After the skillet has cooled to ambient room temperature and the grease has congealed, fully reheat and put another coat of bacon grease over the surfaces of the skillet, again, excluding the bottom. Let the whole thing slowly cool to room temp again.
Once cool, use the flat edged spatula to scrape most of the congealed bacon grease out. Again, be sure not to gouge the cooking surface. Put removed grease in a resealable container and set aside. Reheat skillet a third time but, just long enough to liquefy the remaining drippings. Use a paper towel to smear another light coat of grease over the entire surface area of the skillet, this time, include the bottom.
Place skillet on the oven and heat to 200-225 degrees for about 45 minutes. Turn oven off but, leave skillet onside to slowly cool again to room temp.
Your skillet now has a starter seasoning. However, it will not have the teflon like, non-stick surface yet. That will come with time and proper care and will depend on how often you use it and how rough the original surface was. The more you use it, the quicker it will fully season.
A few pointers.
Always fully preheat your cast iron before use.
Always use some type of grease or oil when cooking in cast iron. This will continue to develop and maintain the season. Over the years, I've found bacon grease and olive oil, in that order, to be the absolute best at obtaining and maintaining a great, hard, slick seasoning. Once fully seasoned, I'll occasionally use real butter.
Always use a flat edged, metal spatula with slightly rounded corners. This will aid in keeping the cooking surface flat and slick especially in newer, rough surfaced cast iron. A metal spatula will scrape the peaks of a rough surface and allow the valleys to fill with seasoning until the entire surface will eventually be even, smooth and teflon like.
Never wash cast iron with soap and water after it has bee seasoned properly. If you do cook something particularly sticky and end up with food particles stuck to the bottom of your skillet, use the flat edged spatula to scrape (not gouge) the cooking surface. If after scraping, you still have some roughness on the cooking surface, use a little regular table salt and a paper towel to scrub the surface. I know this sounds harsh but, for reasons unknown to me, this method does very little if any damage to the seasoning and results in a nice smooth cooking surface. Then, just wipe a light coat of grease or oil on the surface and you're ready to go again.
I know this is kind of long winded but, this is the method, with minor adjustments for modern conveniences, taught to me by my Grandmother who learned it from her Mother. It has served me and my entire family well since at least the turn of the last century. I hope this helps.
P.S. Although I have never tried it myself, a friend sanded the cooking surface of a 14" Lodge skillet in an attempt to replicate older cast iron smoothness. The skillet cracked the first time he heated it afterward. I can't say it cracked because of the sanding but, it had been used for several years prior with no issues so, who knows.