How to restore/upgrade an old bike?

creamster said:

I have an old Peugeot Orient Express. ... Honestly, do you think it is worth restoring?

Pretty much depends on what your aim is and what "worth it" means to you.
And are you looking at an upgrade, or simply to get it back into running order as it were way back when? Assuming it wasn't worn out when you put it aside all you probably need to get it running is wash, lube and perhaps switch tires. That wouldn't cost much.
In general it's bad economy to try to do a thorough upgrade on an older bike. Bikes are so much cheaper when bought complete than piecemeal. Still, a partial upgrade doesn't have to be that expensive, particularly if you manage to pick up some stuff ebay or similar. That could work as long as you're only looking for something to ride for the fun of it without becoming competitive or anything.

Quoted post said:

If so, what would be some suggestions on improvements/upgrades?

First off, take stock. What features of the bike as it is are you most unhappy with, and what parts of the bike are actually worn out? Not knowing what the bike came equipped with it's hard to advise, but you could look into a suspension fork, new brakes, new rear derailleur and shifter. If you're stubborn enough there's probably a way to get a few more gears in there even without fitting a new rear wheel.

take it to a bike shop and ask them because with out seeing it my self i wouldnt be able to tell you if its even safe to ride, so take it to a shop and if they say its ok have them tune it up and ask what might be good to upgrade it with.

~Scott