Budget Atlas Strategy for Leveling and Currency Farming
This strategy is ideal for players aiming to complete the Atlas solo without purchasing maps:

Focus on using Orbs of Horizon to complete unrun maps and upgrade them to Path of exile currency magic or rare quality for increased drops.
Avoid expensive unique maps initially.
Spend chaos to complete cheaper unique maps.
Prioritize completing normal maps, cheap unique maps, invitations, and bosses like Searing Exarch/Eater of Worlds to accumulate 120 points for progression.
Alch & Go Atlas Strategy for Low Budget Builds
Once most maps are completed and expensive unique maps are finished, transition to this strategy:

Basic Skill Tree (54 pts): Establishes a foundation for efficient map progression.
Shrine & Harbinger (76 pts): Utilizes shrine buffs and additional drops from Harbinger encounters.
Expedition (117 pts): Focuses on currency farming, leveraging logbooks or direct Expedition runs.
Blight (117 pts): Tailored tower defense strategy, suitable for non-meta builds.
Legion (115 pts): Enhances drops from Legion encounters.
Ultimatum (120 pts): Maximizes rewards from Ultimatum encounters.
Searing Exarch: Chosen over Eater of Worlds for POE currency for sale better staple currency drops.