I hope I have what is a straightforward question.
Sorry, but this is pretty much the exact opposite. Scalability is a large set of design choices that pretty much need to get baked in from the start if you want it to be super easy. It's generally a lot of extra work, and if you've never built such a system before it's usually just easier to learn by "growing pains".
Our generic canned Answer to these questions is: deal with scalability later. Build your site/application/whatever, and throw a beefier server at it as long as you can. Once that option runs out, start worrying about how you'll split logical layers (which is generally the easiest), like front end web server from the database server. Then figure out how to run two web servers simultaneously, and so on.
A major part of the problem is that while I can waive my hand and say "database sharding" or "active-active clusters", the actual implementation of those is going to depend quite a bit on how your application works internally. LAMP isn't even very "standard" - I assume you mean PHP or Perl, neither of which play well with concurrency out of the box (and will probably be one of the first bottlenecks you'll deal with; at least these are common problems and there's plenty of articles around on how to deal with it).
Update:
I'm having some trouble actually finding a concise outline of scalability topics. I ran across this:
- Stateless application
- Loose coupling
- Asynchrony
- Lazy loading
- Caching
- Parallelism
- Partitioning
- Routing
A similar outline from a different source:
- Separation of Concerns (presentation, logic/app, data, transit/routing, management)
- Minimize Distribution of State (ie, state doesn't cross the aforementioned separation)
- Redundancy
- Separate Environments (Dev, QA, Stage, Prod)
- Build
- Automation (scripting, build, management, etc)
- Configuration Management
- Central Identity Management
- Deployment Management
- Run
- Monitor
- Reassess Capacity, Plan
- Logs, Logs, Logs
- Continuous Improvement Cycle (Agile Dev at the extreme)
I could write a book breaking out each of the subjects in the first list into individual technologies. Each of those could have a book written about implementation on various platforms, different models, and more (many already do have books about them).
If anyone want to add more to this, or add details, feel free.