Well, if you have a newer Wii then a hardmod is not an option for you. You can put one in but it won't play backup disks no matter what. There is a chipset in the newer Wii's (a year or newer) that blocks that. If that's your case then your only option is to softmod and use a hard drive for your backup games.
Softmod is much easier then a hardmod to install. Everything is done from an SD card with a softmod. If you go the hardmod route then you have to open up your Wii and solder the chip in (if you get the solder type). I highly recommend a softmod. You will have a lot more options that way including many, many cool Homebrew apps.