You could use the corner exploit. I got Marco Veratti to 54 league goals in one season using it. 70+ goals a season is a massive achievement, and I think you should be happy with your players scoring 45 goals...
Without exploits it's hard.
How many players IRL have you seen scoring more than 70 goals season?
Exactly. And quite frankly it's offputting to see these things, in FM12 with the Grid Tactic, Park Chu Young Scored 63 goals in around 45 games for Arsenal with me. LOL. And Podolski scored 51 in 43...