Hi Neville,
I've kind of good experience with PLR.
I'll share my experience here.
1) It's depend on the niche you're involved with. If IM niche, there're lots of the same/similar products out there..you have to work harder in establishing the PLR product such as give more powerful BONUS. SO that people will choose your offer instead of others.
2) It's better if you can REBRAND it to other/new name with new graphics, sales letter, & so on. This will make it more UNIQUE at the first sight of your readers/visitors.
3) Use email marketing coz it works for me for this kind of product. This way you have more chances in presenting to your subscribers that you & your product are "real guy" for their resource.
4) I nearly forgot this one, it should be NUMBER 1 from this list. Make sure it's a HIGH QUALITY PLR product. We want to help others while at the same time we receive "payment" for our services. How to make sure that it's a HIQH QUALITY product?
The way to do this is by making sure that the product really deliver the promises. If the product is about weight loss, it MUST give real advice @ knowledge on how to loss weight.