Dave, I too am a relative newbie to Spread Betting. I have fallen into all the traps even though I had read about them before:
Don't trade when you are bored
Don't hold a falling price (sell short/hold long)
Trade with a plan - know your entry and exit points
Dont trade to try and make up a previous loss.
I played around with a few Demo accounts when I started and had a go at trading Apple. The moment I hit the sell button, I was £125 down. This was my introduction to the 'spread' (difference between the buy and sell price). This needs to be as small as possible.
I have now settled on a strategy which involves using stop orders and watching economic announcements. Harry has an economic calander on this site here - http://spreadbettingbeginner.com/news/economic-calander/
, which shows the upcoming events and the degree of impact on the markets. I look for a 'three red bull' event and then trade on the index it relates to. I use a OCO (one cancels the other) order and place a trade order just below and just above the current price. Then, if the market 'spikes' because of an unexpected announcement, the appropriate order will be filled and the opposite order will be cancelled.
This doesn't come without risk though, a number of times I have watched as a price slowly comes down towards my buy order, just touches it to activate it and then rebounds back up quickly, mounting up the losses. I used to swear that there was a programme on the spread betting company platform that tests people's stop orders. This does happen, but its the market that does it, not the spread betting companies
You might also want to look at the forum posting titled 'Demo Trading'. The user 'aster2' uses a scalping technique which he gets quite a bit of success with.
Good luck with your trading Dave.