Need guide for using DL dvd writing

Hi guys
I have used dvd dual layer (verbatim) twice, quite a while ago and very successfully with dvd decrypter (iso read and then write). Thereafter every attempt fails and cost a lot of money.
Can somebody perhaps (and please) explain the details on how to do it right.
I have: DVD Decrypter, Imgburn, DvdFab Gold, Nero and a LG 4163B dvd writer (rom). Work on Windows XP
Looking forward hearing from you

Dual layer writing? Burn it like you would burn single-layer discs, that’s it actually…
How do those attempts fail? What kind of error do you get?

Also what kind of discs did you use, DVD+R DL or DVD-R DL? I am asking because the 4163B does not support DVD-R DL.