Xenoblade Chronicles

Best driver for each blade/weapon at endgame is an easy question to find answers for.

My question is, how should I be spending core crystals throughout the game? I know that at endgame Rex can bond all blades, but I would wager that using no crystals on him for a massive portion of the playthrough is likely not a viable option for a novice.

Should I just feed each driver equally? Is there something I should fish for, and then back off the bonding once I have it? What do I need to have a serviceable team in the early-to-mid game? What mistakes should I try to avoid in regards to giving crystals to drivers?

I'm not asking for a 'good build'. I'm asking for 'a methodology for developing a good build as I progress through the game'.

An adjacent question is what to do with Tora/Poppy? I'm personally not a fan of Tiger-Tiger and would rather not interact much with it, but the DLC pack gave me a bunch of ether. I suspect I can't use that ether to completely make her an endgame fighter (and I wouldn't want to do that even if I could), but I figure I might be able to buy upgrades for Poppy to make her a serviceable crutch until I can replace them with a standard driver. Any suggestions on how viable this method would be, or how to go about doing it?