The ease of preparation as well as the fine tuning of their chemical composition makes layered double hydroxides (LDH) very attractive for a large variety of applications. The aim of this feature article is to provide the keys that permit to finely tune the structure of the materials in controlling simple parameters involved in the synthesis procedures. In a first part, the influence of the synthesis parameters on the crystallinity and morphology of MII-FeIII LDH (MII = NiII, MgII and CoII) is studied. In a second part, further insight into the variability of composition of the layer is proposed to explain the interdependence between the cationic nature of the layer and its layer charge flexibility. The third part is devoted to the anion exchange property of LDH. We showed that a previously proposed method for anionic exchange can be successfully applied to all couple of cations in their range of composition. Finally, a molecular description of the interlayer organisation is given.