Normal or Intense train speed until you can cap it at 49. Then train it to 51 or so while multi-training your next 3 attributes, which are agility, catching and something else. (It doesn't have to be a major, so don't get tied to confidence & vision. You can just as easily make your 4th attribute a minor - like carrying or jumping)
As soon as you get 30 BT, unlock multi-training for those 3 attributes. As BT accrues over time, upgrade each one to 30%. Once speed is trained to 90% or higher and at 51 or so, you should have enough SP to take it to the next cap. Do so, and swap out speed in your training regimen for whichever attribute you want to focus on as your 5th most important.
If you plan on boosting every season, take speed to at least 81. If you don't plan on boosting at all, or infrequently, I wouldn't go to 77. Plan accordingly for the next attributes. Boosting: Agility to 77/81, Catching to 73/77. Non-Boosting: Agility to 73, Catching to 73.
