There was a guide that was written here a few months ago on how to claim secondary coins from a split. Look for the tutorial for the BCH one as it will mostly be the same process as Bitcoin Gold. For wallets, I prefer using Electrum since it is light, but if you can run Core then it is better.

Regarding the tutorial, you can check this link out.

You can keep your coins in a wallet which supports the BTG and has the ability to export the private key. If you have the private key to your wallet you will be eligible to claim the free coins after the fork. You can also keep your coins on exchanges like Bittrex and Yobit as they are supporting the BTG fork and they will be giving equivalent amount of BTG to BTC holders. I would strongly recommend you to move your coins to Bittrex as it is safer than other options and you will be able to trade the BTG as soon as you get it. This will give you an advantage to make quick decisions whether to sell or not while others will be still waiting for their coins to arrive.