The math
You placed 500 bets of 10 each (turnover 5000) and finished +150. Yield = 150 / 5000 = 3%. If your working bankroll was 500, ROI on it is 30% — same result, different denominators. When comparing tipsters, yield on a large sample is the honest metric.
Sample size is everything
Variance dominates small samples: even a genuinely profitable strategy regularly shows losing months. Judge yield together with the number of bets and CLV — positive CLV on a big sample is stronger evidence than any short profit curve.