The first - and in most cases, the only - step is to download all your data from Graviex and upload them to Koinly. There are a few ways you can do this:
If you decide to import CSV files, you have to make sure to import your deposits/withdrawals and trades for ALL years !
That's all you have to do. The only other thing to be vary of is to tag your airdrops/forks so they appear as Income on your final crypto tax forms!