There is more to installing SDL Tridion R5 than simply clicking 'Next'. The following few simple guidelines can help you install SDL Tridion R5 in a way that leads to less issues and better results.

The top 10

1. Install SDL Tridion software on a suitable partition
   
   Most organizations split the server up so that the server has one disk for the operating system and another disk for applications. Install SDL Tridion software on the application partition. 
2. Have separate SDL Tridion Service Accounts for each environment 
   
   If you do not create separate accounts, all environments use the same account and a developer who locks the account when testing something will cause production to stop working. 
3. Install everything 
   
   Don't waste time on deciding what you need in the future, make sure you install all SDL Tridion components and simply disable what you don't need. It will then be already installed when you need it later. 
4. Install as default as possible
   
   Whilst Tridion supports many different installation forms, the less customized your installation, the less likely you are to run into an installation issue. 
5. Move the Transport, Content Delivery and Application Monitoring logs to the logs directory
   
   By default these logs appear in "tridion\bin\logs", where the "tridion\logs" directory is more obvious and logical 
6. Test all parts of the application
   
   Make sure all parts of the installation are working before you declare the installation finished. 
7. Don't forget maintenance!
   
   Ensure that the search collection and database are optimized. Also, consider setting automatic cleanup of folders such as the preview and log directories. 
8. Leave a copy of the software on the server
   
   Also, don't forget to include scripts or tools you used to install SDL Tridion software. 
9. Create a "_patches" directory in the Tridion root
   
   Place a copy of all the hotfixes you apply to the server in this folder. This will make it easier to remember what fixes you installed. 
10. Document your installation   

This will make someone else's life much, much easier.