In my humble opinion:

1. 70% is not difficult to achieve.
2. You can still lose bags of your hard-earned even with 70% winners, kiss your stake goodbye.
3. Predictions are just one stage of three to earn consistent profits. Without the other two, kiss your stake goodbye.
4. Single person sports such as tennis, golf etc are unsustainable - profit wise - for all but the most dedicated punter, kiss your stake goodbye.
5. Low scoring games like soccer etc have high margins of error, kiss your stake goodbye.
6. Pyramid &/or doubling-up type schemes, kiss your stake goodbye.
7. Pay close attention to the gossip, or 'noise', kiss your stake goodbye.
8. Split your stake amongst several systems, because you didn't do the homework, kiss your stake goodbye.
9. Remain optimistic no matter what, kiss your stake goodbye.
10. Dwell on what I - and others - say.... kiss your stake goodbye.

Score: one positive (no.1), nine negatives.

Figure the odds.

But a very few do profit. Listen more than speak, keep an open mind but a tight wallet, and trust your own research not other's hot air.

Good Luck

Captain Max