We had a family newsagents/CTN for over 20 years and I have acted as accountant for several in more recent years. The key to success is:-
1. Exceptional Customer Service - in such a competitive market, you really have to do something special to keep the customers coming to you rather than buying their papers and the supermarket, especially given that newspaper reading is declining anyway. Never do anything to lose a customer - they're all valuable. Sack any paper boys/girls who are late, don't close gates, screw up the papers, get them wet, etc - don't give a news delivery customer any excuse to stop their papers - they are your lifeblood! Ensure service with a smile and help the customers.
2. Don't limit yourself to the same boring magazines and papers that the supermarkets sell. Work closely with the wholesalers to make sure you have virtually anything you can get that is SOR. The vast majority of titles are not readily available, so get the shop known as somewhere to buy the unusual ones.
3. If at all possible, get a lottery terminal, paypoint terminal (for phone and utility top ups), accept credit cards. Get a photocopier in the shop. Get a cash machine in the shop. Offer fax sending and receiving as a service. Offer a payphone. Do absolutely anything to give people a reason to come into your shop rather than go elsewhere.
4. Seriously think about becoming an off licence - profits are small, outlay for stock and security is huge, but it brings in the punters who then tend to buy other things as well.
5. Think about groceries. Whatever you do, don't just be boring and sell the same old stuff as garages. Get some refrigeration and do a good range of milks, yoghurts, cooked meats (packets etc), speciality pies (not like the garages), sandwiches, cheeses. Do fresh fruit and veg. Get a freezer and do frozen meals, frozen veg, etc. PLEASE do it propertly - you won't get anywhere selling a load of canned/processed rubbish, Ginsters or Park Farm Pies, McCoy crisps, bags of spuds, etc which is where a lot of people go wrong. Also make sure you get a good range of heavy stuff, washing powders, washing up liquid, bleach, etc. Don't go for cheap/value lines - get the usual well known names and sell at cost or a little above - you aren't doing this to make a profit, you're doing it to get the customers into your shop. Put in a microwave so that customers can heat up their own pies/pasties for lunch - or even better get a hot food box and get pies/pasties brought in newly cooked from the local bakers.
6. Open even longer hours. Don't close at lunchtimes, don't take half day closing, open seven days, all day. People won't make the effort to come back if you were closed the last time they came.
7. How about something completely different, any hobbies you have. One shop turned itself into a model railway shop, another became the areas main die-cast car seller. How about pet foods, hay/straw, heavy tins of dog food?
What you need to do is get the customers in by enticing them with what they want, even if that means little profit for you. Once they are in, there's more chance of them buying the more profitable items such as news & mags, cards & stationery, soft drinks, etc. With the range you have, you are just another "me too" shop competing for the same customers as every other local CTN, concenience store and supermarket.
What you need to do is forget the conventional idea of CTN's - they belong in a bye-gone age that won't return.