Samsung DVD VR355 DVD format problems

Question

I have a Samsung DVD VR 355 recorder combi and am trying to copy videos onto DVD and I need to be able to play them on PC/Mac and on DVD players. Ive tried DVD R and DVD-R, they copy okay but neither work on PCs or on other players. I was able to copy and play a DVD RW but don't want to waste RWs due to cost. Should I be formatting the DVD media somehow before I press record? Appreciate any advice you can give!