Draw the main components and how they connect. Start simple.
Most systems have:
- Clients (web, mobile)
- Load balancer
- Application servers
- Database(s)
- Cache
Draw these first. Then add components as needed: CDN for static content, message queue for async processing, search index for full-text search.
Don't over-complicate. If you can solve the problem with boxes, don't use . Add complexity only when the requirements demand it.