As an addendum to what Paco has said - the weather needs to be commensurate with the speed you are going to fly. If you are going to be cruising from A to B at 100 kts, you are going to need much better vis than if you are doing circuits at home base at 70 kts. If you are just going to hover taxi around the airfield, you can do it in much reduced conditions. Anything that takes you out of your comfort zone eg busy traffic, unfamiliar area etc: add on an extra to your personal minima to help your situational awareness.