I'm a Salesforce certified developer, very much expert in both Salesforce administration and development. I have developed various custom applications to optimize the Salesforce capabilities using its native technologies.
[1] Developing CRM applications using programmatic tools: Building Apex classes, triggers, Visualforce (pages, components, email templates)
[2] Developing applications using declarative tools: Workflows, process builders, validation rules ... etc.
[3] Salesforce administration: Creating reports and dashboards, profiles, users, page layouts, global and custom actions, security access, public sites as well as migration tools (mainly Data Loader) and Salesforce communities.