Finding the best and cheapest accommodation is always important as most of the time with just a little bit of research you can get accommodation far cheaper and infinitely nice than staying at some over-packed hostel.
Some options to consider are:
Home-stay: Usually you can get quite nice accommodation for around $100US a week, which is much cheaper than using a hostel in somewhere like Amsterdam where an 18 bed doom would cost $25US a night.
Apartments: Sometimes it can be cheaper to use Craigslist or Gumtree to find an apartment to rent, or you can always look for a short term let, rent is usually around the same amount as a home-stay but without having to worry about waking anyone up when you get back from a long night of exploring.
Airbnb: Is quite a cheap and easy way to either rent out a room or an entire house and the rates are quite cheap due to the prices being set by the owners.
Another website that’s almost exactly the same as Airbnb is Tripping, Tripping seems to be a bit cheaper than Airbnb but has less members.
Discount Hotels: Yeego is apparently quite good for booking discount hotels, though I don’t tend to stay in Hotels.
Camping: If your heading to Europe like so many people do a good website to see camping sites is campingeurope