I believe the "buy and hold" strategy is not really applicable to the crypto currency world at this time. The swings are too wild. For crypto currency, a better strategy would be "buy and sell" or "mine and trade". Buy low and sell for a bit higher than the purchasing price to make a small profit. Don't be greedy, some gain is better than no gain or a loss. The end result is really trying to make some gain for each transaction.
The other strategy is to "mine and trade" - mine a crypto that has a relatively high value and low/medium difficulty and trade it for another crypto with a higher potential, and yet more difficult to mine or cannot be mined. Even though the coin you are trading for may have a lower value now, it doesn't mean it's not better. Always evaluate a crypto based on it's primary function and the team and projects behind the coin. Another food for thought is trade your mined crypto for some stakeable coins, so you are building up your assets over time and hopefully you can be a masternode. At that time, you are in a position to reap dividend and just let the money works for you and not you working for the money.
A few more ideas:
Look at new coins, the ones with a relatively small community and looking to grow. These coins typically give out bounty as a way to get the words out. In addition, these coins are easier to mine, if mine-able.
"Buy and stake" - to start off, if resource is limited, look at cheap stakeable coins. Staking allows your assets to grow, without building a rig. The cost of staking your coins on a reputable site may be 1%-3% of your profit, but may be more cost effective than spending thousands of dollars on building a rig. Building a rig requires both money and technical skills. It's a big investment.
Evaluate the exchanges before you transact with them. Each exchange is different in terms of the fees they charge, the level of support they provide, and the coins they allow to be traded on their platform. One important note is not all exchanges allow you to cash out. In fact, most only support crypto to crypto transactions.
Please do not take any of the above content as financial advise, it is solely personal opinion.
Cheers!