Adhesive labels are dangerous because they can unbalance the disc during playback thereby causing read errors. Pressure-sensitive adhesives will break down over time, particularly when exposed to the heat generated by players, and the labels can damage/ruin a player if they peel off while the disc is spinning. In addition, if the media itself is cheap, it is possible for the adhesive to penetrate the disc surface thereby rendering the video/disc unplayable.
I have had problems with adhesive labels peeling on cds when playing — it definitely gives the term gumming up the works a new meaning.
You can print directly to the disc via thermal or a disc printer. Thermal printers are inexpensive and work great but the biggest drawback is the inability to print in more than one color at a time if you want to use multiple colors you will need to create multiple templates. A number of companies make disc printers; Epson produces numerous models with the R200 starting around $77. I use a thermal printer (Casio CW-50) but Im burning discs only for myself, family and a few friends so nothing really fancy is required; if I were doing it commercially I would get either the Epson R300 or R800 (highly recommended by a friend).
As for media I started out using the Verbatim white face dvds mentioned by Lucian. A couple of months back I tried the silver face discs and have decided to stay with them simply because they are 20%-25% cheaper. I am paying around $30 for a spindle of 50 at newegg.com.
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