For my platforms (I/O one on each side) it had been neglected for years and had a couple cracks that previous owner had shot a couple screws through but were loose.
First I disassembled the cracked bits and used "Titebond III" a wood glue advertised as weterproof, clamped tight to position and shot a couple screws through the cracked bits.
I lightly sanded the platform with 150 grit since it was kinda bad, then blew off with compressed air, scrubbed with a soft bristled brush, more air, then about 6 coats of teak oil with 30-45 minutes between each. Basically kept oiling until it stopped soaking it up. Mine were really dry but came out nice.
I put one coat of oil on them last month as they were fading a little bit. It's easier to just do a quick oiling a couple times per season than let them go, then you don't need to sand either.
Here's a pic I have part way through... Never took any pics when they were finished.
http://i121.photobucket.com/albums/o234/cadunkle/Marlin%20Cobra/P1020139.jpg