What to see:
Papagayo Beaches. It costs 3 euros per vehicle to enter the Los Ajachesnational park, and you will have to drive on a super bumpy road, but it is completely worth it. You will find intimate fine sand beaches between cliffs, calm turquoise water to snorkle in and views everywhere . Just know there is also a nudist beach nearby, so be prepared to see a few naked dudes if you decide to explore.
Teguise. It's a lovely typical town located in the middle of the island. There is a market every Sunday, which makes it super lively, but also crowded. It's worth going, but I liked it a lot more when we went back and the town was quiet and empty. You can also climb your way up to the Castillo de Santa Barbara built on the volcano nearby.
Famara beach. This is where you go if you want to surf. The waves are beautiful, but the background is breathtaking too.
Mirador del Bosquecillo. It's located on top of a cliff, next to the telescope, in Lanzarote's only "forest" and it offers a spectacular view. You can also check Mirador del Rio, but there will be an entrance fee.
El Golfo and Charco Verde. Lanzarote is famous for olivine inclusions in the magma. A nerd's paradise! The best place to find them is between Playa Janubio and El Golfo. Just know you are not supposed to take them with you. In that area, you can also stop for the caves of Los Hervideros and the famous green lake of Lanzarote.
Los Volcanes natural park. These lava fields are the result of the 1730 eruptions... so let's say they're still "fresh" and free of vegetation. You will eventually drive through the park and trust me, it will feel like you are on another planet sometimes.
What to avoid: For obvious reasons, I can only advise not to go on a camel ride or to the Rancho Texas zoo. But you should also avoid the Timanfaya National Park. They will basically charge you a 20 euro fee to let you drive to the parking lot of a restaurant. Ok, the view is very nice.... but 20 euros?
I was super happy about my whole stay but this was also my first time travelling as an eco-conscious tourist. I think there's a few tips I should share with you in case you want to go too:
First of all, you will most likely need to rent a car or a scooter if you want to do the sightseeing.
The water is drinkable, but it tastes terrible, so you will have to prepare it in advance to let the chlorine evaporate and/or boil it.
You can't really avoid single use plastic. Most restaurants serve condiments in tiny packages to and you will eventually end up with straws in your drink, even if you asked for none. Bringing your own produce bags and shopping bag will make a huge difference already.
You can survive as a vegan. At first, it may seem like a meat eaters paradise. But because there are so many brits there, there are many indian or asian fusion restaurants. Just make sure to ask which dishes are vegan or not. Most british restaurants also offer options like veggie burgers (and they're usually good), vegetarian full english breakfast (just ask for no eggs). We also tried 2 veggie restaurants (Bistro Arbol and Blooming Cactus) that were very vegan friendly. Worst case, you can decide to make your food yourself, but it will be hard to avoid packaged food when you buy groceries.
I hope all these were helpful and I suppose that if you are reading this, might be travelling to Lanzarote soon, so enjoy!