Here's the approach I've evolved, after watching people get substantial side effects, yet not showing those effects at the same dose when we arrived there more slowly:
Alternatively, you can use the "sprinkles" capsules (so named because for kids you can open them and sprinkle on food). This approach allows you to create 7.5mg doses by opening the 15mg capsule. Do that over food and you won't lose any! Using this approach you can go extemely slowly with dose increases.
Side effects? Confusion and loss of balance have been the limiting factors to using this medication for a lot of my patients. It's been called "The California Drug -- it makes you thin and stupid" (Californians can take the joke; they get to live there, after all). Remember, some have been able to tolerate doses that caused these side effects by going back to a tolerable dose and increasing more slowly. The confusion starts with having trouble remembering names -- first proper names, then names for everyday things, and then even how to do basic things like making cookies from scratch even though you've done it a hundred times before. The balance problem can be severe -- one of my patients fell into her oven and burnt her arm catching herself. Ok, you got the message: be careful!