Best strategy is focus on 1 investment first like bitcoin, accumulate it for few years while learning its pros and cons before you procede to altcoin investing. It's less-risk and less stress for a person doing that approach.
from my own perspective focusing only on one investment like bitcoin is not really a good Idea, because bitcoin is not a get rich quick scheme where you will you centralize all your focus investing on bitcoin alone and forget about investing in others things, remember it takes time to build an investment portfolio, so why not spread your money across other investments like stocks, bonds, commodities, real estate and others, to enable you accumulate more bitcoin consistently and hold on to your bitcoin investment for long term to make reasonable profits.
Responding to the bold word altcoins, altcoins are shitcoins with no store of value and potential returns they are not wart investing on, altcoins (shitcoins) are not less risky rather they are more riskier than you can even imagine. inclusion focus only on accumulating bitcoin and hold for long term and forget about altcoins (shitcoins).
Other investments also do take time to build , rather than finding other investments to diversify on . Try looking for other sources that will help you to sustain yourself while you build your bitcoin investment, yeah bitcoin is not a get rich quick scheme so you take your time to build it well not jumping into other investments.
You have to get to a certain extent first in your bitcoin investment before thinking if diversification. Maybe then you can now think of other things you can invest on , if you start to do more than one investment at a time it will only slow you down , build your bitcoin stash first then find other stuff you can invest on .