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?
In my opinion, if you decide to invest every week, it would mean smaller amounts to invest and the better option is to focus on the two leading coins on the market - Bitcoin and Ethereum. Both are expected to make a big rise in the future. Litecoin is also a pretty good coin, but if you need to split your investment it is better to do it between BTC and ETH.