This document specifies methods for sample preparation to ensure representativeness of the samples throughout the preparation procedures to produce general analysis samples. Suitable test portions can be taken from the laboratory or general analysis samples and used for analysis in conformance with the specific requirements defined in the corresponding analytical procedures. This document specifies the correct sample preparation sequence to be applied to: a) the field sample in order to produce a laboratory sample (taking into account large pieces of solid recovered fuel); b) each sub-sampling step throughout the testing program; c) the laboratory sample in order to obtain suitable test portions; d) ensure the representativeness of the test portions that have been taken according to the sample preparation plan, prior to physical and/or chemical analysis (e.g. extractions, digestion and/or analytical determinations). The methods described in this document can be used for sample preparation, for example, when the samples are to be tested for bulk density, biomass content determination, mechanical durability, particle size distribution, moisture content, ash content, ash melting behaviour, calorific value, chemical composition, impurities and self-heating properties. The methods are not intended to be applied to the very large samples required for the testing of bridging properties.