I've been golfing for about four years now, and am still waiting on my first hole in one.
A hole in one is dependent on the following number of factors:
1) Total number of par-3 holes played
2) Total number of greens landed
3) Distance that each ball rolls on the green (six inches of roll versus 13 feet of roll)
4) Ability to select the right club (for distance (controlling the y axis))
5) Ability to hit the ball straight and at the pin (controlling the x axis).
Therefore, to increase my chances of getting a hole in one, I need to work on all five factors, although factor two is related to factors 4 and 5 for obvious reasons.
I need to play more short courses, and increase the number of par-3 holes played per round. For example, at Pruneridge it is a nine hole course and six of the holes are par-3s. That is a ratio of 6:3, or 6:9, depending on the metrics.
The shorter the hole, the better chance I have of landing the green.
The more pure the swing I have, (high shot with back swing) the more roll I will get.
The more I can accurately judge the wind and distance of each hole (accounting for pin placement) the better chance I have of landing the green.
And the more I work on my technique, the more I can shoot the ball straight at the pin.