A method for forming a fiber-reinforced composite structure comprising the steps of: a) providing at least one preform (10) comprising at least one first ply (14) and at least one subsequent ply (12) wherein each of said plies (12, 14) comprises a thermoset and/or thermoplastic resin matrix and fibers and wherein the direction of the fibers in said first ply (14) is different from the direction of the fibers in said subsequent ply (12); b) helically winding said preform (10) around a mandrel (20) from a first end region (21) of the mandrel to a second end region (23) of the mandrel and/or from said second end region (23) to said first end region (21), such that the direction of the fibers in the first ply (14) is orientated relative to an axial direction (X) defined by the mandrel (20) so as to improve a certain performance; c) as an alternative to step b), helically winding at least two preforms (10a, 10b) around the mandrel (20) from said first end region of the mandrel to said second end region of the mandrel, one (10b) of said preforms being wound clockwise and the other (10a) of said preforms being wound counterclockwise, such that the direction of the fibers in a ply of at least one of said preforms is orientated relative to the axial direction (X) defined by the mandrel (20) so as to improve a certain performance; d) repeating steps b) or c) until the successive windings of the preform (10) define a specific three-dimensional structure; e) compacting with pressure said specific three-dimensional structure; f) consolidating said specific three-dimensional structure through the application of a heating cycle as required by the resin systems.