Welcome to the forum Josh. I too am new to this as a business and am just getting started. However, I have thirty years cleaning experience in the cleaning business. I am going to give some input here to help you get started at home.
Use solution with 0000 (Quadruple ott) Steel Wool. Spray glass a little. Work glass with steel wool. Wipe with towel. Spray glass again, just a light mist. Wipe with second clean towel until dry. Bam! Beauty! Edit Addition: Hey Josh, the smearing is probably laundry soap and dryer sheet film on towels. Don’t use dryer sheets or fabric softener on window towels. I buy CHEAP used towels, big and small at Thrift Stores.
Buy a cheap window “mop” and squeegee to learn with. If you have money, get a commercial 12 inch Ettore or Unger squeegee. Practice, watch videos, practice some more. Now, if your are going to start a business, live on this web site and read. Use the search engine above to find topics of interest using keywords like: door hanger/ WFP/ Window cleaning solution etc. There are 10 years of topics on here in those archives. I have studied this web site now for 6 months. One person says they have read a gobb posts on here. The pros will help you get started but you gotta do the leg work, home work, and learning curve window work. If you work for someone else you will get trained and make some money. But when you leave they may have you under a no compete clause so you can’t start a business in your/ their area. Also, I use store bought products. They are all great for “wiping” windows. I use cotton towels; they absorb, but can leave lint, because glass is rough, not smooth. You can use lint free cloths on a second pass like micro fiber towels, damp glass towel or blue “huck” towels. Practice with juices on mirrors, but don’t use steel wool on mirrors. Have some fun and go make some money. This is edited. Thanks pros!