Hey guys! I am very new to cryptocurrency and I am seeking advice on how and where to invest
Holding your bitcoin on hardware wallet will be best, but you can try electrum if the amount to hold is not much, the electrum official site is electrum.org. To buy, you can try hodlhodl or bsiq exchange, or making use of this forum for buying.
I do not have enough to buy an entire bitcoin. I am wondering if it is better to buy altcoin and convert it to bitcoin later
You can purchase even $10 worth of bitcoin or less, you do not have to by 1 bitcoin. What you should consider most is to buy low and it's price to increase so you will gain. If you buy the altcoins at high price, and if you want to sell, you will lose and nothing different. But altcoins price can be more susceptible to depreciation during bull back.
That's why I am seeking your advice and getting involved in this community.
My advice for you is to know the historical price of bitcoin and be conversant with technical analyzes. Be careful of scammers and have your online privacy.