You can deduct any and all “ordinary and necessary” expenses. Common deductions include office supplies, office equipment, wages paid, the cost of goods and services, vehicle mileage, office costs (including home office deductions), licensing and certification costs, education and training costs, uniforms, software, applicable utilities, 50% of meals for client and business relationships, and more.
Generally, track ongoing expenses such as software licensing fees and business account bank fees, and also track incidental expenses like office supplies, meals, mileage, etc.