It's not enough having an investment plan, knowing the right choice to make for every investment defines the investor better. Take for example jumping on every new coin we find on reputable exchange might not be enough guarantee that coin will do well in the future.
Even top reputable exchanges also sometimes listing a quite questionable assets, it's up to you to filter which assets are promising to trade and not. The exchanges are just collecting some money and it's up to the traders to do the rest, you can't just blindly follow top exchanges and feeling safe right there. It doesn't work like that.
Some coin might have good Supply but low liquidity, some might have high market capitalisation but very poor volatility. Although it's hard to predict the accuracy of a coin performance in the near future this why it is always advised to stick to the known which is BTC.
That's the top recommendation for most of the people, but if you are feeling the confident with your picks and want to learn something with trading then it's a good idea to try out some of the altcoins out there.
Another option is to spread ones portfolio amongst different coins but ensuring the have a greater percentage in projects with a visible future. It is better to win small and lose less than lose more and win less
Make sure to do some research first and have a spare time to actually manage the picks.