diff --git a/README.md b/README.md
index a2b3255ff083461a088bc70ce50c26a368f21921..b4535b5a7c57b975ba4c9fa2d7b40c29d57f003d 100644
--- a/README.md
+++ b/README.md
@@ -6,7 +6,9 @@
 
 ## Description
 
-MetaSnk is a modularized Snakemake workflow for the analysis of metagenomic datasets from human microbiomes.
+MetaSnk is a reproducible and scalable modularized Snakemake workflow for the analysis of metagenomic datasets from human microbiomes.
+
+MetaSnk wraps system and software dependencies within Singularity containers.
 
 ### Modules:
  - [rawQC](README_rawQC.md)
@@ -59,6 +61,13 @@ MetaSnk is a modularized Snakemake workflow for the analysis of metagenomic data
 
   Notice that you can have multiple paired fastq files per sample, but each SampleID-RUN_LANE combination must be unique.
 
+- sample_metadata.tsv: a tab-delimited table with at least two column fields
+
+   ```
+   sampleID SubjectID
+
+   ```
+
 ## Usage
 
 ### Simple
@@ -79,6 +88,13 @@ If you intend to modify and further extend this workflow or want to work under v
 
 In any case, if you use this workflow in a paper, don't forget to give credits to the authors by citing the URL of this repository and, if available, its DOI (see above).
 
+##### Create minimal environment
+
+Some rules will use this environment.
+
+    conda env create -f ./envs/MetaSnk.yaml
+    conda activate MetaSnk
+
 ##### Download singularity containers and reference databases
 MetaSnk wraps system requirements and software dependencies within singularity containers.
 Download these containers by running rule 'pullSIFS' :
@@ -99,12 +115,6 @@ MetaSnK uses reference databases that need to be downloaded to the $METASNK_DBS
 
     snakemake --profile ./profiles/local buildDBS
 
-##### Create minimal environment
-
-Some rules will use this environment.
-
-    conda env create -f ./envs/MetaSnk.yaml
-
 #### Step 2: Configure workflow
 
 Configure the workflow according to your needs via editing the file `config.yaml`.