Thoroughly endorse Andy's reply above. We always travel independently and have a number of rules that we stick to. We always book our flight direct with the airline. We find that Christmas Day/Boxing Day are a good days to book from a price point of view. We do, sometimes, book accommodation via such as Booking.com (normally transit accommodation for the odd night or two whilst waiting for the ferry we want) but always on a 'pay in resort' basis and always with the price in Euros, not Pounds. That way, the price you see is the price you pay at the accommodation. You are asked for a Credit Card number to secure the room but you don't have to pay with that card when you get there. We use a pre-loaded card that enables us to buy Euros at a time when we think there's a good rate and use that card to pay or to draw cash on in resort if we're paying cash. If we book direct with the property owners then they, sometimes, ask for a deposit up front normally equal to one nights cost. That's as much as we pay up front and, whilst it can be a bit of a rip off to do a bank transfer for that deposit, it's never much, really, so it's not the end of the world. So far (touch wood) in 20 or so years of booking our holidays this way on islands up and down the Dodecanese we've only ever had one bad experience and that was in 2015 on Patmos where we ignored our own rules and paid for some accommodation in advance. We did get the full amount refunded but only after the intervention of the helpful and friendly manager of the Alpha Bank branch in Skala who wasn't at all happy with his hotel owing customer (long story but Patmos has one hotel that we'd recommend be avoided at all costs despite the, mostly, glowing reviews on Trip Advisor etc.). Even then, that experience did have a silver lining as we found an alternative as late afternoon 'walk ins' at the Hotel Skala in Skala which was exceptional and is recommenced very highly by us.
Steve