What's the best strategy to play against a tight player with a small calling range when HU?
I know that aggression usually pays off, but when they start calling a lot their ranges are either widening due to pressure or they are running with some playable hands.
P.S. will check out some HU videos
HU play is not the strength of most MTT players 
Therefore you won't get many answers I guess.
My approach would be to grind him down preflop and give up postflop if he is really tight. It will take some time but you should get his stack bit by bit. If he is a bit more into calling pre I will contibet a lot.
It's obviously hard to give tips for HU play. Every opponent is unique in his playstyle and therefore needs unique adaptions. Watch him and try to find ways to exploit his style.
Regards,
Asaban
Yah, Daniel negreanu showed a really good video of grinding opponents pre flop in h/u with simple strategies. His opponent was tight enough but grinding him will get him looser. Try finding it on youtube 
