I want to start practicing both GIS and RS on software "R", how and where to start it initially? Any recommended books or sites for tutorials. is highly appreciated.
I have always found tutorialspoint a really good website for tutorials across a broad range of programming languages: http://www.tutorialspoint.com/r/.
Also stack overflow is a good platform if you have any questions/problems with R: http://stackoverflow.com/questions/tagged/r.
By far the most useful is google, if I have an R related problem I usually just type "R my question" into google.
Once you're getting the hang of it, you can start looking into tutorials that are specific to your problem. For example there're plenty of GIS tutorials: https://www.google.co.uk/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=R+GIS+tutorial.
as for start-up , i recommend you to start reading basics of R programming from this book "An introduction to R by Longhow Lam" . This book is basic text book for R language.
You can try also to read (extra option) from " S-PLUS® 7
Programmer’s Guide " . You find this book as starts for S language. R language is more resemble with s language.
Size of these books is very high. You can collect from me manually. I can provide my time voluntary-related to your query in R language.