Algar Seco and Carvoeiro: go early, park once and walk
Algar Seco and Carvoeiro are close enough that there's really no reason to treat them as separate outings.
My advice is simple: go early, park once and use your feet.
You'll avoid some of the parking hassle, see Algar Seco before the day gets too hot or busy, and you can easily combine it with breakfast or lunch and some time in Carvoeiro afterwards.

Start with Algar Seco — especially when it's hot
If you're coming in summer, I'd start at Algar Seco.
It's a place for wandering around rather than looking at from a viewpoint. There are paths, steps, rock formations and little places to explore, and you're exposed to the sun for much of it. Early morning simply makes it more pleasant.
You don't need to make a military operation out of arriving at dawn. The point is not to leave Algar Seco until the hottest part of the day.
There is parking around Algar Seco and the nearby streets. If you arrive early, you can normally park around the Algar Seco/Earth/Vimar area and leave the car there.
That's what I'd do.

Then decide when you want to eat
A few minutes' walk away is Earth Shop & Café.
If coffee matters to you, this is where I'd send you. It's my favourite coffee in Carvoeiro, and the breakfasts are substantial enough to keep you going for quite a while.
Earth opens at around 08:30, so you can also reverse the order:
That's a lovely version when the weather is comfortable and you're in no particular hurry.
On a hot day, I'd do the opposite:
One useful detail: Earth may stay open until around 16:30, but the kitchen closes earlier — roughly 15:30. Don't arrive late in the afternoon expecting lunch.
Check current opening and kitchen hours before going; these can change.

Walk from Algar Seco towards Carvoeiro
From Algar Seco you can take the boardwalk towards Carvoeiro.
It's a short, easy stretch along the cliffs rather than a hike, with plenty of reasons to stop and look around.
And eventually you arrive at the other side of the Carvoeiro equation: the little town itself.

Carvoeiro is touristy, but I like it. It's compact, lively without being Albufeira, and everything converges around the small beach in the middle of town.
Walk around. Go down to the beach. Have a drink. Sit somewhere and people-watch.
You don't need another attraction.
If Earth isn't where you want to eat
Almost opposite Earth is Vimar, a small family-run restaurant.
This is where I'd go when I want straightforward food that tastes homemade without spending a fortune. It's not somewhere I'd send you for a fancy dining experience. That's precisely why I like it.
If you want the more indulgent version of the day, continue into Carvoeiro and go to O Pátio.
My choice there is very specific: spaghetti alle vongole, followed by their panna cotta with Silves orange.
That's the version for when lunch itself is part of the outing rather than something you need because you're hungry.
So which way would I do it?
It depends.
Hot summer day:
Cooler day and breakfast matters:
You mainly want Algar Seco:
That's probably the main thing I'd tell you.
Don't spend the day collecting stops. Algar Seco, good food and a wander around Carvoeiro are already a very good few hours.
A note from La Casita
This is one of the combinations I recommend to guests because everything fits together without much effort. From La Casita, Carvoeiro is close enough that you don't need to devote an entire day to it either.
If you tell me what kind of day you're after — beach, walking, food, sightseeing or mainly doing as little as possible — my answer might be different.

