Just some feedback.
The difficulty with trying to trade for old sets, as that many users that have them value them higher than the infinite sets that come out now. Their value is easier to assign since they have a specific print count, rarity and pack odds that makes trying to compare them to new sets difficult.
Also, there is the fact that if the old set is out of free packs, or out of print, many value these cards at a higher worth, since ways to get these cards are now only by trading.
Many users will not part with these prints easily, as their value is often-times higher than what most offer. For myself, I typically only trade them for equally hard to get pieces.
In specific example - Places to Hide sold out very fast - and the print count for this set is so low, this will be extremely hard to find people to trade with. Your best bet would be to look at each owner, and see if you can find pieces in older sets they collect and offer those. It will be more about helping them finish something they have been working for - and a bit of luck.
Older sets are a challenge my friend - but if you can collect them - the journey is almost just as worth it.
Good luck and Happy Collecting (and Holidays)!