Hello Guys

Im a lover of Linux, i am studying to get LPI 1,2 and maybe any other course to improve my knowledge in Linux's Word.
Please based on your experience, which distribution is better to train, and maybe one guide the important thing to study and follow.
Appreciated

Linux From Scratch, Slackware, Archlinux

Likely RedHat or its derivatives, CentOS/Fedora (as I believe the original LPI were created using it).
However, the most used systems used by companies & internet services are Debian & RedHat.

The best distribution is probably the one you like! All distros are much the same at command-line level — a few configuration files may be differently named or in different directories, but that's all — and the command line is what's used on servers.

Businesses that pay for support use Red Hat (particularly in the USA), SUSE (particularly in Europe), or Ubuntu (cheap). Organisations which have in-house expertise (e.g. internet and computer companies, universities) go for the free CentOS, Debian Stable, or Ubuntu. Distros like Slackware and Arch are very good, but not common outside the homes of computer buffs.

So, consider
OpenSUSE (the basis for SUSE Enterprise Linux)
CentOS (the free version of Red Hat) or Fedora (the basis for Red Hat)
anything Debian based: Debian, Mint (Ubuntu tidied up), etc

Whatever you choose, get to know the command line if you have a professional interest in Linux. For day-to-day use of the GUI, look at the ones available
http://www.renewablepcs.com/about-li...-gnome-or-xfce
and consider a distro which specialises in one that you like the look of: SUSE or Kubuntu for KDE; CentOS, Fedora, Debian or Ubuntu Gnome for Gnome; Mint for Mate; Xubuntu for Xfce.