if I think personally a safe way to invest in cryptocurrency is :
1. the project runs according to the roadmap and whitepaper that has been made;
2. cryptocurrency that we invest in already has a product;
3. the team always updates about the progress that is happening in the project that we invest;
4. invest in project that are in the top 1-500 in coinmarketpcap (have a high volume);
5. the project we want to invest has been running for a long time (if I personally never invested in a new project), because investing in new project has a greater risk than we invest in old project.
If you want to have safe investment you should be investing in top 10 cryptocurrencies. For my own opinion, there are still good new project and if you are risk taker you should invest on the new good project. Always check the chart in the market and monitor the price of cryptocurrencies that you have. Lastly, always remember spread your investing in different cryptocurrencies and take note of this quote "Do not ever put all your egg in one basket".
Commonly, we see those lines. And if we take it logically, there's really a good significance to spread and split your investment, unless you are playing inside like gambling with fate and if you believe that the market can bring good outcome to your chosen project. Nonetheless, split and work with new and old projects that have products that offer long successful ventures.
Open yourself to new ideas that can put your investment to further success, observe and address all the potentials that are listed above from OP's list.
Logically all coins will have a low price at some point. Invest in the coins wisely and in a fast method.