VFR cruising levels (semicircular rule)

Applies above 3000 ft AMSL (or the applicable transition altitude, if higher) when a cruising level is required.
Track 000°–179° (magnetic): odd flight level/altitude + 500 ft (e.g. FL035, FL055, 3500 ft, 5500 ft).
Track 180°–359° (magnetic): even flight level/altitude + 500 ft (e.g. FL045, FL065, 4500 ft, 6500 ft).
The +500 ft offset from IFR levels is what keeps VFR traffic vertically separated from IFR traffic on the same semicircular scheme.
Unlike for IFR, compliance with the VFR cruising level table outside controlled airspace is good practice but is not itself mandatory — always follow any ATC instruction or established traffic pattern first.

Source: SERA.5015 / SERA.5025 – Table of cruising levels