"Travel, poor … even when ... you don’t have to." 

I. Hostels:           I'll assume you are already familiar with hotels, AirB&Bs, etc so I'll skip their discussion.

Hostel’s are NO LONGER just for youths. Originally designed for young backpackers traveling inexpensively, hostels were 'rough' & simple;  a cheap building converted for multi-bed dorms, basic kitchen, bathrooms & showers, simple laundry facilities & maybe a common room for relaxation and conversation, -- ALL at a low price.  

Today they are often much more.

Today, most hostels provide  the above basics & much much more:
    a. 4, 8, 12 & more bed dorms at a scaled pricing
    b. single & group rooms for singles, couples, school groups & families
    c. all ages except the very young & Unaccompanied.
    d. occasionally bathroom is attached to each dorm room
    e. washer & dryer & occasionally laundry service
    f. friendly communal dining & kitchen areas with full amenities
    g. comfortable common room
    g. Wifi
    h. secure luggage storage
    i. currency exchange
    j. Travel Desk & day tours
    k. Special Events:  movie nights, cooking classes, etc
    l. security: hostel entry, rooms & lockers
  

Greatest hostel benefits, IMO,  vs. hotels etc. are:
    a. Full Online information & booking
    b. friendly staff:
        1. often well-traveled; just working before moving on
        2. English speaking staff who know city & surrounding area well.
    c. guests
        1. friendly & informative because are your fellow travelers.
        2. shared camaraderie, tales & advice: hostels, cafes & transport,
    d. fellow SIT travelers who may relish each evening's dinner chats.
    e. guest's share travel experiences in common room or during meals.
    f. create your own day trip with dorm-mates & a car rental.

Compared to hotels etc. which, IMO, have a chilly business-like atmosphere with mechanical staff & expensive amenities. While Air B&Bs may be homey, both hotels & AirB&Bs are self isolating, lacking the pleasure & reassurance of shared hostel's camaraderie.

 II. Booking Strategy:

    A. International Arrival: 1^st couple of nights

When 1st arrive in host country from USA, I have already pre-booked my 1^st couple of nights to recover after tiring flight(s), reduce any anxiety & easily acclimate.

    B. ... to next city:

I don't recall visiting any town or village that did not have even the most basic lodging available. Usually a hostel, partial home conversion (Japan), old hotel, small B&B,

Hong Kong’s ratty, semi-scary, cockroach infested 😃 Chungking Mansion’s pseudo-hostel room & bath.                                                 [ytlk:China:] 

or even the single room in older woman's Batopilas home at bottom of Mexico's Barranca de Cobre Canyon (Copper Canyon).   

1. My Practice:   I would either --
        a. pre-book:  via the Internet (hostel world.com, booking.com, etc.), if I had or was confident I could get a bus/train ticket so I could be assured of my arrival time, or …

       b. take my chances if I could not be sure where, and when I would arrive or if Internet lodging options were sparse.

           Anecdote:  Leaping Tiger Gorge hike: I just kept walking into early  evening to 1^st available refugio/hostel & meals. [ytlk: CHI: Tiger Gorge].

           Anecdote:  Camino de Santiago trek:  Trekking Camino de Santiago in Spain there were many lodging options in each small village en route each day that I just waited untill I arrived. However, as travel dramatically increased, I found it necessary to book earlier and longer to avoid frantic search for same quality lodging. [ytlk: CdeS.

CAUTION: Travel on the Camino today may be much more intense now and booking may be required. Beware.         

2. Key Hostel Info: 
        a. Confirmation number, address, phone number, and contact info, if any any. TIP: Store hostel’s Google Map’s pinpoint in cell phone.

        b. Backup list 3>4 additional hostels that I had screened & with contact info in case I choose to change hostels.

        Anecdote: Tallinn, Estonia:   My Tallinn's  1st ratty-hostel included
a nightly live rock music bar which made early sleep nearly impossible. I moved the next day to a  superb hostel (Wait for it!) … for the same price.  [ytlk: Estonia, Tallinn