People with Colour Vision Deficiencies (CVDs) face notable difficulties in our society that uses colours as a tool of communication in various situations related to design, architecture, traffic, education, etc. Daltonization recolouring tools are a popular strategy in image processing to improve colour perception of people with CVDs by increasing chroma and lightness contrast between confusion colours that are difficult to discriminate for people with CVDs. However, recolouring tools often fall short in practical applicability due to not taking into account basic requirements of various colour tasks, and an insufficient assessment by real people with CVDs. In this paper, we provide guidelines for the design and evaluation of Daltonization recolouring tools to increase practicability and enable their comparison with each other. Namely, a good recolouring tool for people with CVDs (i) should preserve naturalness and originality where possible; (ii) should preserve good colour identification and/or connoted meanings of colours. (iii) should sustain colour communicability consistently throughout the workflow; (iv) should enable customization for different types and severities of CVD of individual users (i.e., it should be open for the integration of different models of the human visual system (HVS)); (v) should define the visual goal of the recolouring tool; (vi) should name the target image type(s) of the tool, e.g. photographs, information graphics, maps, charts; (vii) should account for general restrictions of the medium both in acquisition and reproduction, and should acknowledge challenges related to colour management; (viii) must be tested using real observers with CVDs; and (ix) must be tested on different types of images.