What are the most cost-effective exterior updates to improve curb appeal for a quick sale?

I would suggest you start with what you mentioned. You want a desirable curb appeal that will make people want to get out of their car. A green lawn, powerwashed facade, siding and curb/front porch, some bright colored plants for spring, fix any obvious cracks or visible holes, paint your foundation if it is cracking, paint the front door, make sure your lights are bright and bulbs are all working for night showings, clean windows, etc. This should be a good start.

You’re focusing on exactly the right areas, because buyers form their first impression before they even get out of the car, and small exterior updates can completely change how your home is perceived. Start with a thorough cleaning, a good pressure wash on the siding, driveway, and walkways can make everything look brighter and better maintained almost instantly. Your front door is another easy win, a fresh coat of paint in a clean, inviting color draws the eye and makes the entrance feel cared for without a big investment. Landscaping also makes a noticeable difference, trim back anything overgrown, remove dead plants, lay down fresh mulch, and add a few simple plants or flowers near the entry to create a neat, intentional look. From there, it is the smaller details that really pull everything together, a new doormat, updated house numbers, a clean or replaced mailbox, and a simple, modern light fixture by the front door can subtly elevate the entire exterior. Make sure the windows are spotless, screens are clean. If you have any areas of chipped or faded paint, touching those up helps everything feel more cohesive. The goal is to make the home look clean, maintained, and easy for a buyer to picture themselves in, because when the outside feels right, they walk in with a completely different mindset.

Freshen up the land scaping. It needs to be trimmed, tidy and inviting. Trim all the bushes and trees, pick up down limbs and debris, mow the grass, plant some brightly colored flowers and apply fresh mulch. Curb appeal is a huge factor in attracting buyers. Paint the front door and have the house power washed. You don't necessarily need a new roof and new siding as long as those items are functioning as intended.