Define the environment before the CAD
Consider sunlight, temperature, rain, standing water, vibration, chemicals and how long the part is expected to remain in service. “Outdoor” is not one condition: a shaded garden clip and a black bracket inside a parked vehicle see very different temperatures.
Design around the print orientation
Printed parts are anisotropic. Orient the part so important loads are not relying unnecessarily on weak layer-to-layer directions, and use generous radii or fillets where stress would otherwise concentrate.
Plan mounting points carefully
Fasteners and clamps can create local stresses. Use adequate wall thickness around holes, washers or inserts when appropriate, and enough clearance to avoid forcing a printed part into position.
Give water a path out
Avoid accidental cups and pockets that hold rainwater. Drainage holes, slopes and open-bottom geometry can reduce trapped water and debris around fasteners or electronics.
Validate anything safety-critical
ASA is useful for durable outdoor parts, but material choice alone does not qualify a component for safety-critical structural service. Test the actual part, load case, environment and filament grade before relying on it.