are this the correct steps, to keep my BTC the whole time during and after the fork secure and also get the free BTG?
1. Keep BTC in a wallet where I have the private key.
2. Waint until fork + airdrop of BTG is done.
3. Move BTC to a new wallet, where I control the private key.
4. Move BTG to an exchange and sell it.
If one makes this step by step, will one then be secure against replay atacks and so on?
Is step 3 necessary and recommended?
Or do you prefer an other way to be secure and also get BTG and be able to sell it?
Just make sure that the wallet in which you are saving your Bitcoin will give away free bitcoin gold to their bitcoin holders. Otherwise, you will end up with zero bitcoin gold. I think the better way is to store them to a wallet, or even exchanges such as bittrex, that already made their official commitment to provide bitcoin gold to those people who are holding bitcoin in their wallets. After all, this happens for a few days.