There are a few different ways to trade on Coinbase without fees. The most common way is to use a limit order, which will allow you to set the price you want to pay for an asset and only buy or sell when that price is reached.
Another way is to use a market order, which will fill your order at the best available price. You can also use a stop-limit order, which will only execute your order once the price reaches a certain level.
If you want to avoid fees altogether, you can use Coinbase Pro, which is Coinbase’s advanced trading platform. Coinbase Pro doesn’t charge any fees for trades, but it does have a slightly higher minimum order size.