Plan 1: Buy BTC and ETH only. Spend $50 and buy 50% BTC and 50% ETH. No schedule and buy on dips.
Plan 2: Buy BTC, ETH, and LTC. Weekly, regardless of the current cost of each coin. Alternate between coins so 1 week buy 50/50 BTC and ETH. Next week buy 100% LTC. Next week buys 50/50 again.
HODL both obviously.
Also at what point is a hardware wallet required?
Plan 2 seems to work for me, but for the next week, I will buy 50% BTC and 50% LTC, and I am not going to use 100% for LTC or ETH because bitcoin will be my number 1 investment.
Hold will be the next plan after I have all of that coins and not selling for some time or until the price increase so high.
You can use Ledger or Trezor to keep all of your coins, and after you bought those coins, you can send them into that hardware wallet and keep it.
But besides that hardware wallet, you can install a mobile phone wallet that supports bitcoin and altcoin. That can works good for you if you do not have more money to buy a hardware wallet.