High-contrast imaging (HCI) techniques appear like the best solutions to directly characterize large orbit planets and planetary environments in the future. The first dedicated scientific instruments like SPHERE on VLT and GPI on Gemini South have only been commissioned in 2013-2014. HCI is thus a rather young field of research, still very prolific with a lot of technical solutions proposed to improve the actual instrument concepts. A lot of new technical solutions have been recently proposed to improve actual instrument concepts. Since most of them have not yet been tested at the expected level of performance and/or in real conditions, it is rather difficult to define precisely which solutions will be the most efficient scientifically with respect to the future technical, environmental, and operational constraints. Among these different solutions, I will describe and discuss the main directions of development required to optimize the future HCI instruments on speckle suppression, wavefront correction, and detection methods.