What’s the best advice you have on saving/investing money as a 20 year old?

So for general investments you pay tax if you go over the capital gains limit (3k iirc), this includes standard interest paid on savings accounts in your bank. You get a £20k overall limit on ISA contributions per year and anything the ISA makes is completely tax free. Within that overall £20k limit there's specific ISA limitations, for example a LISA has a £4k limit per year, from April there's gonna be a limit for young people on cash ISAs (£8k iirc, etc). With a LISA you get a 25% bonus on anything saved from the government when you buy your first house, so for example if you deposit the limit for the next 3 years you'll have saved £12k yourself and the government will give you £3k towards your house. If you're making 5 grand a month and have low expenses you should be blowing past your £20k ISA limits, at that point looking into other tax free investments like premium bonds might be the way to go (£50k limit, 3.6% average payout, all tax free). How you spread your money within your ISA is up to you, I put everything I save in the market but I've already got a big house, got married, settled down - there's not gonna be any major life changes in my future so I don't need my money to be liquid, I can let it sit for the next couple of decades. At your age and in your position the likelihood is that over the next few years you buy a house, you get married, you have kids, in that position having your cash in the market potentially limits you.