First question - did you have a home inspection?

When you buy an older home that has not been renovated there are going to be some large ticket items that don't make things necessarily look better.

You need to know how old your systems are and what will need to be replaced in the next few years. You don't want to spend your money on cosmetic fixes if it won't leave you enough left over for replacing the roof, hot water heater, furnace or AC when they go.

I bought a home built in 1970. I have had to upgrade electrical and add lighting, had to have several trees removed, had to have the roof repaired (another 10 years until it will need replaced) needed to replace the refrigerator and dishwasher, had to have one area of the yard regraded as it was sloped toward the house and I was getting water in one corner of the basement, had to fix gutters, add a spark arrester to the chimney and I spent $11 k in January of this year when my tankless water heater and my HVAC both failed 2 weeks apart. Now I get to have some fun and start making my home prettier.

It is less expensive to have electrical and plumbing projects completed at one time than to have the plumber or electrician do one thing at a time. You need to have a plan and know what all needs to be done and how you can break it out into 1/2 or full days of work.

Your chimney is too low if you have a wood burning fireplace. If it is a gas fireplace the rules are different. Your inspector should have noted if there was an issue with the height of the chimney. It also should not have passed inspection if this was original to the home or a permitted upgrade.

Painting the outside and adding landscaping is all that is really needed. I would leave the sliders until you have lived there at least a year. Depending on your climate it may be nice to have the enclosure.

Make sure that there are no trees too close to the house that may damage the foundation of your home.

​Given the era you believe it is from, I think the green area would originally have been in a shingle style or maybe verical wood in a brown paint. A modern take on this could be to use battons and create a vertical siding in cedar or larch. It could be just in the triangle or could extend to the ground leaving the stone / brick work as a feature. Once the glass enclosure is removed the porch area could be painted  dark charcoal.

Fix the important things first. Cosmetic improvements second. That being said:

For a quick inexpensive improvement in looks, paint the green gable and the green trim under the gutters the same yellow cream as the walls. Check the garage for extra paint that may have the computerized color info on the label.

Which are newer and in better shape: the white windows or the black windows? Are they paintable wood or unpaintable vinyl?

I agree theinterior is the first step to get all the must haves done first Electrical, plumbing, HVAC maybe even windows . BTW often when you renovate an interior even window placement is changed so stop worrying about the exterior right now . I do see the chimney extending above that gable so it is probably hiding behind that somehow. Since the roof seems to need attention I would start there since if the roof caves in you have no home,