For the 'Visitor's Guide to Skiathos' type of sites, you can of course just 'Google' "skiathos".But this throws up all the 'usual suspects * ' hotel and cheap flight sites, plus of course all the rogue 'loaded-prices' villa sites (see 'Fair Pricing'). So, best to filter the 'Google' results by searching e.g. 'Skiathos Guide' ... but that still throws up a lot of token 'Skiathos Overviews' as a vehicle to hotel adverts, rather than info to help you choose - or hopefully, not choose! - Skiathos.
So I've suggested a few below with rather more substance, like photo galleries of the main beaches, and well thought-out descriptions.
Also - there's much more 'insider' detail in the 'Villa Guest Guide' Parts 2/3 ('Skiathos and the Islands' and 'Some handy Greek; Food and Drink') which I send to everyone booking a Skiathos Greek villa ... or for an advance copy, just let me know in the "Your Message" box, by clicking .... "Enquire Now !", or email / call me at email@example.com / 0033 6 63 42 50 50 (FR mobile)
Links ... (not guaranteed btw - please let me know if you find any that have become insecure etc.)
www.greektravel.com/greekislands/skiathos/ from the reliable well-presented Matt Barret Greece and Greek Islands guide. The home 'Greece' section has a comprehensive 'History' - virtually a site in itself!
https://travelingwiththyme.com/2018/04/skiathos-island-guide-greece/ interesting site by quirky travel blogger Christina X
www.skiathos.gr/en/ the official Skiathos town hall site (btw, at your own risk as it comes up as "not secure" - but unlikely the mayor's trying to hack you!)
www.issuu.com/entosvolos/docs/discover_skiathos_lower/1 This is the Greek/English ‘Discover Skiathos’ magazine;4 issues to view, loads of photos and beaches-what to do-history-etc, and useful hotel-taverna-shop adverts. See copy on villa bookshelf, €5 in shops - e.g. Asteras
http://skiathian.blogspot.com/ more of interest for regular vistors and residents, but the useful 'Pages' menu (homepage on the right) has timetables for the Koukounaries and Evangelistria buses, and the beach water-taxis.
* of the 'usual susects', https://www.tripadvisor.com is possibly the most useful on the 'Guide' side, with plenty of reviews and photos of the the village, facilities, beaches, restaurants as well as hotel accommodation - and an endless "Skiathos Forum" tweeterie with over 5000 entries!
But - definitely not recommended for whole-villa rentals. Although T-A hotel deals are via www.bookings.com etc. and generally discounted from the hotel rack rates, T-A charges villa-rental owners a 10% commission, which most of them build in to their prices.