If you are like most golfers, the long irons are probably the most difficult clubs in your bag to hit consistently. Most mid to high handicappers find it hard to get sufficient loft with the 2 or 3 irons. You have two options here. Avoid the long iron in favor of fairway woods or get to the practice range and work on this part of your game. Probably the greatest problem for most amateurs is that they 'psych' themselves out of hitting good long-iron approaches.
Tension overcomes the swing and a poor shot results.
Sweep the ball off the turf. Hands should be slightly ahead at address. Take the club back 'low and slow'. Transfer your weight early on the downswing. Hands lead the ball through impact.