In order to meet minimum spend requirements, people often look for options to increase spend in ways that result in getting their money back. These techniques are referred to as "manufacturing spend". American Express has terms in their welcome offers that exclude some manufactured spend techniques
from counting towards the minimum spend requirements for the welcome bonus. For example, most new cardmember bonuses have terms like this:
Eligible purchases to meet the Threshold Amount of this offer do NOT include fees or interest charges, balance transfers, cash advances, purchase of travelers checks, purchase or reloading of prepaid cards, purchases of gift cards, person-to-person payments, or other cash equivalents.
That said, many techniques for meeting minimum spend are perfectly fine. Here are some techniques that are safe for meeting Amex minimum spend requirements (click each link for more information):