Many sellers do improvements and upgrades to their homes prior to marketing the home. Some improvements make sense and some just will not be recouped.
Bathrooms and kitchens will add value to a home but your taste might not be what your buyer is going to want.
Before making improvements consider if you have made your home ready for market by making repairs and cleaning/painting first. Some times just simple organization, scrubbing and de-cluttering will be the best investment.
An experienced real estate agent can help you with suggestions and often that advice is available for no charge.