Art history major here! Here's my tried-and-true structure for art history research papers:
Introduction: Hook with the artwork's significance + your thesis (your unique argument about it)
Visual analysis section: Formal elements first—line, color, composition, scale. Describe WITHOUT interpretation yet.
Context section: Historical/cultural background relevant to your argument
Interpretation section: This is where you synthesize your observations with research to support your thesis
Conclusion: Broader significance + maybe lingering questions
For research, use Artstor for high-res images you can analyze closely, and JSTOR for scholarship. Also, your university's art library might have exhibition catalogs that aren't online—those are GOLD for primary source material.
What's your topic/artist?