Tips and tipping services have been around as long as the bookmaker. There's always someone that has 'the inside track', a friend at the stables, or a sure fire money making system.
For all their bluster there's one thing you should know about tipsters; they want you to lose.
There is nothing generous about their sharing of knoweldge and information, it's done so they can benefit from your loses.
What part of this relationship makes you think the tipster wants you to win?
Add into that the clear issue between someone who can predict sports events with great regularity. That's basically Biff in Back to the Future with the sports almanack, whoever could do that would be rich beyond their wildest dreams, not the kind of person you'd expect to be offering tips on twitter to their invariably bought followers.
I've done a bigger piece on snowball betting (also known as rolling accumulators), but wanted to reinforce this for everyone reading. Tips are not the way to winning bets. You're always going to be taken in the end, and that's exactly what the tipster wants to happen.