If you are counting pedestrian-oriented hardscapes in your credit calculations (through SSc2), you need to make sure that at least 25% of the total open space area is vegetated. Be sure that you calculate the vegetated area based on ground coverage and not using tree drip lines.

Make sure that all vegetated and hardscape open spaces are included in the LEED site boundary, and that the boundary for this credit is consistent with the boundary for all LEED credits. 

Will your project achieve SSc2: Development Density and Community Connectivity? Find out as soon as possible. Pursuing SSc2 makes the open space credit easier, because you can count pedestrian-oriented hardscapes and green roofs towards your open space area.

Define your LEED project boundary to determine how much area you must designate as open space. The LEED project boundary encompasses a contiguous area that includes all areas affected by the project pursuing certification. Refer to the Rating System document (p. xvii) for specific guidelines on how this is determined. (See Resources.) 

Consider creating a project master plan that includes long-term plans for open space, helping you comply with SSc9: Site Master Plan.

Designing a project with ample open space can increase the value of the property and may increase rents, especially in areas that do not generally provide these amenities to building occupants. From a purely economic standpoint, however, buildable square footage typically adds more value than open space. 

Discuss the potential for future build-out, and make sure the areas delineated as open space for credit compliance will not be compromised in the future. Consider creating a project master plan that includes long-term plans for open space, helping you comply with SSc9: Site Master Plan.

Discuss the potential for future build-out and make sure the areas delineated as open space for credit compliance will not be compromised in the future. 

Determine your project goals for vegetated open space and pedestrian-oriented hardscapes. 

The owner will need to sign off on the LEED Online credit form as part of the documentation, stating that the open space is intended to remain open for the life of the building.