How do you do perfect, straight ollies?

Hi, I've been doing ollies for about 8 or 9 monthes and they've gone from decent to ok. I'm having problems with them. One problem that I have that seems to always happen is that when I land my front foot is on some what on the on the nose and covering the front top bolts and sometimes land in nose manuel. Sometimes I'll land like that, but with front some what hanging off the toe side of the board. Another thing that will happen a lot is that I'll turn frontside a littlle and then when I land I'll always have to kick turn out of it another thing that happens is my back foot will somtimes be on its toes and I'll sometimes lose my balance and jump off the board. Alos when I try to do a high ollie and I'll suck up legs but then it will feel like my front foot is coming off the board so I'll end up doing a very low ollie. I also have a hard time doing high, far ollies when I'm moving pretty fast. I can never land with my feet flat on the bolts. Any tips so I can do better straight ollies? Thanks!