You can follow the above posts but the risk is, the bots can be detected by twitter audit and it's not recommended if you will use this Twitter account for upcoming twitter campaigns altcoins or bitcoin related campaigns. The most recommended is follow most bitcoin/crypto related twitter accounts, retweet some of their tweets then you have to wait until they follow back.
And when you see some twitter campaigns, of course you will see all the participants in this campaign's spreadsheets, and you can visit all those accounts and follow them since this accounts need also more followers because they need it to earn more in any twitter campaigns, then most probably they will follow your account also.
This is the best method, I'd rather choose this one because you can prevent the account which seems bots or fakes even it is done manually you can assure that you only follows those real accounts. Follow the official twitter accounts that runs a bounty campaigns and also follow their followers.