Start with ECG Basics (79 min, Ninja Nerd), then Cardiovascular (52 min, Ninja Nerd). All 24 lessons here are free, from the teachers' own official uploads. You'll need venipuncture practice arm, scrubs set, phlebotomy exam study guide (about $120 of kit). The book to keep beside you: Phlebotomy Essentials by Ruth E. McCall.