Hi, the Lead (Potential Client) may or may be not converted into an Opportunity. The Opportunity is the actual input of the Sales Pipeline. Opportunities and Sales are managed together (technical object sale.order). If you select a Lead in the Tree View, in the More menu you can start the action "Convert to Opportunities". You should avoid converting all leads automatically to Opportunities, and thus, feed the Sales Pipeline with them. Leads need to be qualified first, such that you can make them appropriate sales offers. Nevertheless, if you want a fast conversion of the lead up to the sale & invoice, look at the Odoo online shop (v8). I hope this helps.