New accounts are best as its the easiest way to build up your bank with simply welcome offers. Profit accumulator and oddsmonkey are the prob the best 2 sites out there for tutorials/software to get you started but they are monthly subscriptions. They used to do a £1 week trail on oddsmonkey but not sure if thats still running. Team profit perhaps a decent place to start as thats all free with a facebook group if you are have any questions.
But too echo what BSK1 says if you have any sort of problems with gambling it prob isn’t for you as most often you can have money sitting around in bookmaker accounts