A properly constructed formwork is the cornerstone of a reliable concrete structure. Do have the formwork inspected and approved by a qualified structural designer before pouring the concrete.
Here are a few guidelines that will help you build quality formworks:
For formwork of ground floor slabs, the props should rest on firm surface, preferably PCC. When the formwork is rested on earth, ensure that the ground is dry and well compacted. Use spreaders for props resting on ground. Avoid the use of wooden props if possible; steel supports are preferred. For slabs, ensure that props are vertical. Load carrying capacity reduces significantly when props are inclined. To fix props, use bracings on both sides and runners at the center. Seal any gaps in shutter joints to avoid leakage of cement slurry. Before concrete is poured, ensure that interiors of the forms (shutters) are cleaned and shuttering oil (form release agent) is applied. Avoid the use of engine oil or other such lubricants as they may stain the concrete surface. During concreting, forms, props, and all other supports must be continuously checked After concreting, do consult your structural designer before removing the formwork.