There are many ways for the forum to get you free coins, but they are usually junk coins, you should not waste time here, you are late.
It depends on what is meant by free coins. If these are airdrops, then it is better not to waste time on participating in them. Revenues are so small that it makes no sense to do this.
If you are thinking of coins from bounty campaigns, then these are no longer free coins; in order to get them you need to do the work, waste your time and skills.