Most Basis are from IT Administrator or DBA staff. They should have good knowledge on their field. Network Administrator has good knowledge on network stuff, router such as Cisco, 3COM, Nortell, etc, OS Administrator has specific knowledge about OS specific command, and DBA has well knowledge about database design, database query, database performance, database daily administration, etc.
If you have one of those knowledge, then that's good point and has great advantages for you. But if you don't have it, don't be shame. All you need is start to learn. Make it fast. That's all.
Depend on what kind of you SAP server and database your company will use, then you'll need to master them. Some operating system are very popular as SAP server such as IBM AIX, HP HPUX, Microsoft Windows, SUN Solaris, Redhat RHEL, and Novell SLES. You need to master specific configuration. Sometime you may tune some OS kernel.
IBM provide great books via redbooks website. You just need to download some of them. HP also provide some books although not as complete as IBM does. You need to buy some books if your company use SUN Solaris. If your company use Linux then you're lucky guy. Linux has numeruous books on internet which freely available to download. You also can start learning before SAP implementation because you can download Linux OS freely from internet.
Database software which are popular as SAP database software are Oracle, IBM DB2 and Microsoft SQL Server. You can start learning them by buying some books. Oracle is the most popular on the planet. There are many books about Oracle on bookstore. Many website and blogs explain Oracle tips and tricks. You can start learning IBM DB2 by downloading some ebooks from Redbooks website. Microsoft also provides some good books about SQL Server.
After you master some of basic configuration about operating system and database then you should be ready to start SAP implemenation. Let's SAP implementaion begin !!