Whatever methods you would have discussed above. I consider myself to follow these things to grow my bitcoins.

1. Convert a small part of my paycheck to buy bitcoin.
2. Use that bitcoin to buy well analyzed low priced and profitable altcoin. Sell it when it doubles or trading in a decent profit.
3. Repeat the same steps whenever you receive paycheck.
4. If you're careful in trading with altcoins it will grow gradually.