Just solve problems. Then learn binary search when you can solve A and B easily.

Just solve problem, hone your problem solving skills bro. Problems under 1800 rating usually don't require complex algorithms. As a newbie, I suggest learning basic stuff like binary search, quicksort (programming languages usually have these thing in libraries, so you don't even need to learn how to implement them, just learn how to use them), look up table, etc., then solving problems from a rating range until you can do problem in that rating more than 80% of the time, then jump to the next 100 ratings (for example: you solve 800 problems until you can solve 4 out of 5 problems by yourself, then jump to the next 100 rating, which is 900, then 1000, 1100, ...). Just jump until you got to 1700 — 1800, at this point you need to learn complex stuff like priority queue, trie, dsu, etc.