The first and usually only step is to download all your data from Cashierest and upload them to Koinly. There are a couple of ways you can do that:
Note that if you want to import CSV files, you must make sure to import your deposits/withdrawals and trades for ALL years !
That's pretty much it. The only other thing to keep in mind is to tag your airdrops/forks so they show up as Income on your final crypto tax reports!