Krusan, what's up buddy?
I wanted to note (and I believe I've stated this before, oh well) but certain officers have a set number of times they can be captured before they join you. For example in any storyline in which Sima Yi does not have a fixed part, if you capture him twice he'll join your side. There may be certain variables such as if you have a "friend" or a certain number of "friends" of his, but as best as I can remember it only takes two captures to get him on your side.
I reference Sima Yi specifically because he is one of the two best strategists in the game IMHO (with Zhou Yu) and he can easily be had early on in many different campaigns. In Wu's longest campaign he can be had in the first scenario versus Wei when he's at Level 3 IIRC, there's a lot of stat boosting you can do when a character is at such a low level!
If you've figured out how to properly level characters up with optimum stat boosting, you can create a darn near invincible army long before the end of each scenario. Here's a tip for one specific character, if you have the item "Feather Fan" you'll get a stat boost of +3 INT per level up and if you have Lu Bu you should leave this on him until Level 15 (or 16 if he's your army's primary leader). Once he's maxed out throw on the item that gives you +20 LEA and the defence lowering affects of Avatar are lessened to the greatest point possible. For Lu Bu you do not need to stat boost him one bit for WAR or LEA, ONLY focus on INT. Maxed out he will always end up with a minimum of 80 LEA so he'll be able to have a 10 unit army and the only additional defense boost he can have is with the +20 LEA item.
More tips to come!
Saint Joan of Arc, Pray for us!