For beginners I reccomend to trade cryptocurrencies from Top 10. Do not mess with little-known cryptocurrencies, if you havn't an insider information...
The points you have made is good ,you need to follow the market really well before investing and understand how things work, the main idea behind it is simple, but for beginners starting with top ten coins means those are high valuation coins that have broken the shell and had a rally, go for low valuation coin with for a small budget and have some experience dealing with it before investing heavily. Right now i would say that it is the best time to invest as the market is on a correction mode for some time.
and right now if we buy bitcoin or altcoins it could give us profits.but some time for tokens/coins with low valuation give us big profits,much people just focus on top coins/tokens.meanwhile other could give them high return.