Keep it Simple
Making an investment plan is one of the less important things you have to do.
Figuring out your values (or what motivates you), living within your means, earning and saving as much as possible, and automating your finances are all more important than what you do with your savings.
Once you have some money saved up for an emergency fund (2-6 months of living expenses is a good buffer) you can start thinking about investing.
There are a lot of options, but to avoid paralysis through choice I would start with something like a balanced portfolio of stock index funds (for growth over time) and bonds (for stability).
Andrew Hallam goes into the details of this strategy in his book Millionaire Teacher, or JCollins has a great series of posts about the stock market here.
If you are eligible for a J401k account I would definitely look into that. If you are not eligible or have extra money to invest check out NISA accounts.
The key is to keep things simple and not overthink your strategy. Once you have a plan, keep to it and over the next several decades your finances will get steadily more robust.
What do you do to invest?