At it is right now, the game allows many avenues to gain training points. You can complete:
Zeke's Quest - This is obviously one of the easier ways to gain training points. No elaboration needed, but, if you haven't completed them all as yet, you can begin to. Guides are also available online to make the quest completion a little easier.
Leveling - Training points are awarded through leveling. They're usually awarded upon leveling every five levels. Example, you'll gain a point at level 5, then at level 10, level 15 etc.
Eloise Merryweather , Zeke's companion also has quests for you (beginning in Azteca) with some rewarding training points. The quest Cactus Blossom Boogiegiven by her in the Caravan is just one such example.
So, as you can see, there's a plateau of avenues that can be taken as it relates to gaining additional training points.
Well of course you get training points every 4 levels until level 20, then it's every 5 levels. Then, in each world Zeke gives a quest for you to find the Smiths/Beetles/Stone Roses etc... after completing each of those you get a training point. If you haven't done it yet I recommend doing Wysteria as it is the quickest of Zeke's quests. Then in Celestia, Ogden Peak has three quests, each gives a training point. In the later worlds, Eloise Merryweather, the Spiral's stitcher who always stands next to Zeke will give 4 quests which each give a training point. They are in Khrysalis, Polaris, Mirage and Empyrea. Other training points can be earned by quests from Inyanga Whitestripes (2 in Zafaria), Francis Lux (3 in Avalon) and Zaltanna the Mirrormask (1 in Khrysalis).
If you don't complete any of the quests, a level 120 wizard can earn 26 training points. If you do complete all quests, it's 54 which is more than enough.