Start by mapping every customer touchpoint in your funnel: paid search, organic, email, social, direct, referral. Implement UTM parameters consistently across all campaigns and configure GA4 to track these interactions as events. Connect your CRM or analytics platform to capture offline conversions if you run phone or in-person sales. You need complete visibility before any model matters. Collect at least 90 days of path data, ideally six months if your sales cycle runs longer than 30 days. B2B services in Ottawa often see 45–90 day cycles, so three months barely scratches the surface. Export this data showing each user's journey from first click to conversion, including timestamps and channel sources. Choose your attribution logic. Linear gives equal credit to every touchpoint, which works for short cycles with 3–5 interactions. Time-decay weights recent touches more heavily, useful when the final interaction actually drives the decision. Position-based (U-shaped or W-shaped) credits first touch and conversion touch at 40% each, splitting the rest across middle touches. Algorithmic or data-driven models use machine learning to assign credit based on actual conversion patterns, but require thousands of conversions monthly to be statistically valid. For portfolios under 500 conversions per month, we typically run position-based models in Google Analytics 4 and compare against last-click to spot undervalued channels. If organic search shows 15% credit in last-click but 28% in position-based, you know SEO assists more conversions than it closes. That changes budget decisions. Implement the model in GA4's attribution reports or export path data to a spreadsheet for custom weighting. Tag every URL with source, medium, campaign, content, and term parameters. Set conversion windows that match your actual sales cycle: 30 days for ecommerce, 90 days for lead-gen services. Run the model for one full quarter, then compare channel ROI under different attribution methods before committing budget shifts. The model that best predicts future performance wins, not the one that makes any single channel look best.