i usually find that i have a problem catching smash shots down the line in singles...and i wonder if ur supposed to lean towards the side of the smash like so... and also, where is ur racquet supposed to be, is it supposed to face the forehand side more or straight to the front?
The most important for smash return is to load your legs. What I mean by this is to take a small hop and land on your toes right after your opponent hits. This makes it so that you aren't flat footed and can move. I personally prefer to keep my racket to the side which offers the opponent the shortest distance to smash. If I was in the middle (which shouldn't happen really) I keep my racket in a backhand grip. Another important thing is to push off with both your legs in the direction you want to go in landing in a lunge slightly stretched out to return the bird. Generally, I would go for a drop return unless it is a really bad smash. Hope that helps a bit.
You should not land on your toes with your last step. It should be heels first then forefoot. This is for balance-landing on your toes will tip you over-whereas landing first on your heels and then front foot will ensure stability and the necessary push-off (from your toes) for your next move.
i think he means the preload little hop to get the movement started not the last step at the end of movment
you should also favour the down the line side slightly more, as it takes less time to get there. if you are in trouble, i'd lift it to the centre. this cuts down the angles your opponent can make and so, it' easier for him to blast it out the side or close enough to you so it's not much trouble. if he hits it at you, even better, you don' even have to move if he's hitting it onto the line even after you lift it to the centre, maybe he's just a bit too good for you.