Choosing the "L"I use the latest Ubuntu LTS, or Long-Term-Service release. This ensures 6+ years of compatibility, stability, bug fixes, and security fixes. CentOS, Red Hat Enterprise Linux, and Debian Stable are other common choices, but for the purposes of this document, I will assume Ubuntu 12.04.
The "A" in LAMP is for the Apache web server, and there's really not much choice in that. Make sure you're running a current version, though. You may also choose which modules to enable or install. I try to keep the server light, and I disable CGI and and deflate. You can enable CGI if you need Perl, or enable Deflate to save bandwidth, but I tend to target script performance and load handling over bandwidth. I also use mod_userdir, which you should install if given the option. On Ubuntu, all of these mods come along with the basic apache2 package.
"M" and "M" (and occasionally another "P")
Although PostgreSQL is also a fantastic option, MySQL is still the de facto standard for LAMP stacks. Future versions of Red Hat Enterprise Linux and Ubuntu LTS will switch to the completely compatible fork, MariaDB, and will keep the acronym neatly in tact. MySQL's InnoDB database engine is nearly ACID compliant, fast, and featureful. For this reason, I install MySQL 5.5 or higher for now, and will use MariaDB when it is widely available. I also often install PHPMyAdmin along with MySQL.
Mind your "P" (or "R" or "L" or...)
The last letter(s) in LAMP are the most flexible. PHP is a common choice, but so was Perl (thankfully, not so any more, though you might still need it with CGI), and Python, Ruby, Lisp, and a few others are also gaining in popularity. I'll focus on PHP, since it's what I mostly develop in, and it is what many common software projects such as WordPress, Drupal, and PHPBB are built on. PHP has a lot of libraries built in, but I recommend adding GD, CURL, and SQLite support which are often packaged separately. Most distributions package the Suhosin (security hardening) patch by default, if not, I recommend you install it as well.
On Linux, getting PHP configured to send eMail is easy. Simply install Postfix, and you're on your way. During installation, you'll be asked for SMTP configuration, so make sure you have that handy.
Accessing the Server
The standard methods of interacting with a web server are SSH, FTP, and SFTP. I recommend ProFTPd and of course the standard SSH server. ProFTPd is my FTP server of choice because it is very easy to set up. You log in with your system account, and your permissions are determined by what they are set as on the server. This makes it secure and easy to configure all in one.
The Magic Command
One of the things I love about setting up Linux servers is that you can get it down to just a few commands. As my parting thought, here's a magical command for Ubuntu flavored servers that will get you up and running in one go.
sudo apt-get update; sudo apt-get install apache2 php5 mysql-server openssh-server postfix proftpd-basic phpmyadmin phpsysinfo php5-gd php5-curl php5-suhosin php5-sqlite; sudo a2enmod userdir; sudo a2dismod cgi deflate;
Tune in next time for how to set up user accounts, access control, per-user websites, DNS integration, and performance tuning for Apache!