https://www.reddit.com/r/BitcoinMarkets/comments/7db1hk/a_method_of_claiming_bitcoin_gold_btg_coins_right/
Also for electrum its is much safer if you create a new wallet and transfer all your BTC to it. Then use the private keys of the old wallet and sweep as per instructions given. This will ensure all your Bitcoin from old wallet to be safe. And your private keys will have only the BTC you had before 25th of october.
Very crucial to transfer your BTC to another wallet first before claiming your btg, do not use freewallet or their official wallet, someone reported to have lost their BTC when they use the official wallet, mybtgwallet.com and there is another clone of it is totally phishing wallet that collect your private key/seed word do not use it, bitcoin gold is totally scam coin
https://www.coindesk.com/bitcoin-gold-wallet-scam-nets-3-million-illicit-earnings/