Buying One Size Primer at Ulta is a simple process that can be done either in-store or online. Here are the steps for both methods:

1. In-Store:
- Locate your nearest Ulta Beauty store. You can do this by using the store locator feature on the Ulta Beauty website or app.
- Once you're in the store, you can ask a sales associate for help or navigate to the makeup section yourself.
- Look for the One Size brand display. The primer should be there.
- After you've found the product, take it to the checkout counter to make your purchase.

2. Online:
- Visit the Ulta Beauty website or open the app on your mobile device.
- Use the search bar at the top of the page and type in "One Size Primer."
- Click on the product when it appears in the search results.
- Add the item to your cart by clicking on the "Add to Bag" button.
- When you're ready to checkout, click on the shopping bag icon at the top right corner of the page.
- Review your order and click "Checkout" to proceed.
- Fill in your shipping and payment information as prompted.
- Click "Place Order" to complete your purchase.

Remember to review the product's ingredients before purchasing. As a skincare expert, I always advise understanding what you're putting on your skin. If you have any specific skin concerns or conditions, it's also a good idea to consult with a dermatologist before trying new products.