What Torvald said.
You are almost guaranteed to be able to max out three stats, so decide early on what you want. Acceleration is generally considered to be the weakest stat, but depending on what course you prefer, and what build you're making (abilities), the others are all viable.

I maxed speed, stamina and cunning, with endurance being the stat I would get as close to max as possible (grade 3 feed only obv, which always gives a flat 15 points to that stat).
Early on, I fed my bird whichever of speed/stamina/cunning was furthest behind, but around lv35 I stopped training and building up my training sessions.

When one of my desired stats hit 455, I would feed it three times in that stat to bring it exactly to cap, and then it is no longer "available" as one of the random stats that can be increased at lvl up. The downside of doing this, is as you then only have four stats available for your random stat increases, it increases the chance that they will be placed in an unfavourable stat (ie acceleration). If you are braver, you could wait until it naturally hits 470 (and feed twice), or if really brave, 485 (and feed once), but you are running the risk that at lvl up it will get two allocations and "jump" from say 480 straight to 490, and then you could be screwed out of a few points.

I ended up with
Speed 500
Accel 300
Endurance 450
Stamina 500
Cunning 500
Speedy Recovery III (hereditary)
ChocoCure III (acquired)