Now, I'm new to this restoration thing, but this is what I've been working on today... and I think I did a pretty good job :)
( Not really seen: spiderwebs of blue lines caused by cracks in the emulsion.)
How'd I do it? I'm not even sure of all the steps anymore, but a LOT of healing brush, clone tool, burn tool, levels adjustment, desaturation of spots, sharpen brush, paint brush, decreased opacity settings... And a few hours.
I'm rather happy of how well this 16 year old slide came out!