Lithobraking is the best way to slow down, so get rid of those useless parachutes. When in doubt, always radially attach SRBs on top of more radially-attached SRBs. Try to get at least 3 solid layers and pack them as tight as possible to eliminate the need for struts. When gravity turning, go horizontal as soon as possible to improve rocket efficiency during launch. Spaceplanes should be aimed straight up when flying to space.