Starting from the top down is always the safest bet when budgeting multi-year renovations. If your roof fails, a water leak will instantly ruin any new siding or interior work you just completed, costing you double. My rule of thumb is to fix whatever keeps moisture out of the house first, then move to aesthetics. We tackled our drafts sequentially by looking at the Harvey Classic window page to compare efficiency ratings before replacing two leaking frames in our kitchen. Keep a close eye on your attic for hidden damp spots this winter.