I tried search this forum for tips about the subject but cannot come up with anything (perhaps I used wrong keywords). Anyway, I have a problem smash on the forehand corner (especially those slow and fast lob). At that corner I often smash to the net. I need a solution. Please help. Most of time, the lobs are fast and low. By the I am close enough to hit, I have to do a swing that is somewhere between side-armed and overhead, with a contact behind my back (it usually goes flat) or a contact in front of me (it usually goes too steeply to the net).
Unfortunately, not clear to me. Do you mean smashing from your forehand corner or do you mean smashing to opponent's forehand corner (cross smash)? Are you trying to do a jump smash? Usually it just takes practice and proper timing to do a smash - ask someone to do some practice shots or even sneak in a "practice-shot" during a game. Good luck.
Dont do a full swing for a smash unless you are behind the shuttle, If you do whilst stretching out to the side, then the consistency and accuracy is reduced. When the shuttle is at the side just push it, or do a different type of shot, wait for the right lift (high and short) for the full smashing motion. It is a common mistake for people to not move enough onto their forehand side, as they think they can reach it . They move to move round the head on backhand side, but dont' on the forehand side, make a concious effort to move nearer the shuttle, so you can perform the correct stroke.