Step 1:

Determine the CO2eq of your flight. To do this find your flight on a site such as google flights and note down the emissions estimate for the flight.

Step 2:

Find a carbon offsetting/removal scheme to make a payment towards. A personal favourite site is Frontier Climate, if you know of other reputable schemes please contact me here.

Step 3:

Decide on how much you should pay towards a carbon offsetting/removal to reduce your net emissions. To this you can use this spreadsheet.