Why I must make Incremental Backup and clone to my Hard disk and what is the best programs or ways you use to do so , is it internet backup safe?

it depend on what applications you have on the server,

using incremental backup will save disk space on back up destination, but if one of the incremental backups defected, you will not be able to perform the restore

if you have an exchange or sql server you need a backup software that support these types of databases

this is an example of backup plan

use Symantec backup exec system recovery  or acronis backup advanced server with universal restore to backup the server as an image with the ability to restore to dissimilar hardware in case of server hardware failure

here is an example

backup the whole server to an external hard disk, NAS or another server, as image

config the backup as full backup on each Monday

incremental backup daily expect Monday

clean up and retention policy to clean up backups older than30 days

the software should allow granular restore in order to restore specific file from image backup, symantec BESR allow restore of email message from image backup if it contain exchange server

as i know, windows server backup tool can only realize full backup and incremental backup, if you want to differential backup, it it recommend you to choice AOMEI Backupper Server edition sotware, at the same time , this software allow you to back up files and system in any place.of course you can read windows server2008 backup to know more functions.such as system and file back, differential and incremental backup,and system clone, disk clone etc.