Informational Poster Design Needed

I need a clean, eye-catching poster that clearly presents information to the general public. The layout should guide viewers through the content at a glance, using clear typography and a balanced visual hierarchy.

Core requirements
• Size and orientation: please recommend a standard print size that works well for noticeboards and digital sharing.
• Color palette: choose colors that enhance readability and suit a broad, non-niche audience.
• File formats: deliver a print-ready PDF (CMYK, 300 dpi) and a web-friendly JPEG/PNG.

Visual approach
I’m open to different visual treatments—whether that’s strong photography, custom illustrations, concise icons, or a thoughtful mix. Feel free to propose what best supports clarity and engagement.

Timeline & collaboration
Share an initial concept with sample fonts, colors, and a rough layout; after feedback, refine it into the final artwork with up to two revision rounds.

If you have poster designs in your portfolio that showcase information elegantly, include them so I can see your style.