Start by considering your profit margins, average conversion rates, and the lifetime value of a customer. Tools like Google’s Keyword Planner can give you estimated cost-per-click for terms relevant to your area, helping you gauge how many clicks you can afford daily or monthly. Decide how aggressive you want to be—if you’re in a competitive niche (like accountants in Chelmsford), you may need a higher budget to outbid rivals, whereas a niche service in a smaller town may require less. Also consider your overall marketing objectives: do you just need brand exposure, or are you aiming for immediate leads? Test small campaigns initially, measure results, and scale up if the return on ad spend (ROAS) is positive. A flexible mindset is key; you may need to adjust budgets seasonally or based on new data to maintain efficiency in your local Essex market.