I know all the TV shows say the Kitchen and Bath. Well I suggest you start with what is called "Curb Appeal". If people don't like the outside look of your home - they aren't coming in to see your new kitchen and bath.
Make the outside clean and neat. Painting if needed, The Front Door and storm door need to be in great shape, also the door knob,steps.
Windows should all be clean,bushes trimmed,grass fertilized,prune any wayward tree branches. Some plants on the front stoop. Mailbox new or like new. In other words make it look as nice as you can from the street. No kids toys scattered in the yard- no old car your working on sitting apart in the driveway.
Then start in the entryway, kitchen,bath.
A clean house is a must. Depending on the house square footage and bedrooms you may want to add a bathroom. It is well worth the money to have a master bath, another full bath for the remaining bedrooms, and a half bath at the lower level for guests to use.
The kitchen is next. Sometimes just updating the light fixtures, the hardware on the cabinets,flooring,countertops,appliances, paint. And you know replacing the cabinets would be great - but sometimes you don't have that much money.
The house not only needs to be clean - it needs to smell clean. If you have indoor cats,dogs get that smell and hair out of the house.
Be prepared for buyers to start deducting from your asking price if there are things they will obviously need to repair, if there is too much- they won't even bother with an offer.
Your central air is a must - they will already expect it to have that so you are not going to get any return on that expense.
Go through some houses about the same size and costs as your planned listing amount- see what the competition is like.
Pretend your house is going for a job interview - what do you want it to look like?