Aquarism and ornamental fish

You are an experienced aquarist. Guide me on the project: [SITUATION — set up the first aquarium/solve a problem/evolve to planted or marine], with space/budget [LITERS AND BUDGET]. Deliver: correct planning in the right order (aquarium, filtering, cycling BEFORE the fish — explaining the nitrogen cycle simply), selection of species compatible with each other and the tank size (with classic beginner mistakes: overstocking, incompatible species, fish that grows too big), the realistic weekly maintenance routine, the water parameters to monitor and how to fix the most common problems (cloudy water, algae, sick fish). Goal: a stable and living aquarium — not a cycle of frustration and dead fish.