For the note on practice, I try to practice weekly, or at least several times monthly. I'd do more if I could swing it but finding time for even that is becoming tough.

When working on weaknesses, remember how the events are scored. You get a point for each place, so a 1st place finish gives you one point, a 9th place finish gives you 9 points. Lowest point total overall wins the aggregate event. In the strategy of the games working on your worst event will probably pay off more than trying to improve your best event.

For example, I know that with my stones I am going to be top three. I could improve them a little, but odds are I will still be top three depending on the field. First place by an inch or by two feet still gives only one point.
Now my worst event by far is my WFD. I usually come in somewhere around 5th in those depending on the field, yet even a small improvement could see me placing top three. If I can get those numbers up I can go from a 5 point showing to maybe a two point showing, shaving three points off my total score. A similar improvement in stones might net me only a one or two point reduction.

If placing is a concern to you, practice your best event just enough to stay in touch with it but work on your weakest events the most. By getting all your scores consistent you'll end up much better off over all.