This really varies by market and property, however in most cases I’d say curb appeal first.
After that, are there inexpensive updates you can do to the kitchen or baths? Those rooms are usually what sells the house. Repainting or touching up paint can make a big impact without spending a lot of money.
No matter what, make sure you declutter the house as much as possible, make sure it’s very clean for photos and showings, and hire a good listing agent who will get professional photos and put effort into marketing your property.