If you are funding your GDAX account by directly linking your Debit card, you may start off by only being allowed to fund $200 dollar worth of crypto coins daily. In order to ncrease your deposit limits, you should do the following:
Establish a purchase history by buying and selling within your account. i.e. Under your funding limit in Coinbase you will see a milestone to reach in order to have a limit increase. Just like below.
So in this case if the account is funded with $250 twice, it will qualify for an amount increase.
Click here for more information on limit increase.