Manually Choosing Transaction Fees
For ETH and ERC-20 transactions, you can use https://ethgasstation.info/ to find the appropriate gas price you can be using to minimise your transaction fees.
Enable "Advanced Mode" when sending a token and enter in the Safe Low or Standard gas price into the "Gas Gwei" field. The Safe Low amount can be expected to confirm within 30 minutes, while the Standard amount is expected to confirm within a few minutes.
For Bitcoin transactions, you can use https://bitcoinfees.earn.com/.
Enable "Advanced Mode" when sending BTC and change the "Satoshi per byte" field to match one of the suggested prices on the left column. The estimated confirmation times are displayed on the right-side of the rows.
Automatic Fees for ETH & ERC-20 Transactions
The Enjin Wallet automatically sets an estimated transaction fee to allow for a quick transaction. If you want a quick transaction but aren't looking to manually check and minimise your fees, then you can leave the fee slider at the automatic default.