After 45 minutes the wheel was somehow wobbling worse than before I started" - yeah, that sounds about right for a first try. One thing though: you mentioned spoke tension being off, but you might be confusing tension with the actual truing process. Spoke tension is about how tight each spoke is (measured with a tensiometer), while truing is about adjusting the rim side to side. You can have a wheel with wildly different tension on each side, but if the rim runs straight, it's technically "true" even though it's not built right. The wobble getting worse usually means you were turning the wrong spoke nipples, or you were overcorrecting by tightening too many spokes on one side without loosening the other side first. Try starting with the tightest spot, loosen it a quarter turn, then tighten the two spokes around it an eighth turn each, and see if that helps next time.