The key to a well funded retirement, and in fact to a stress free financial life, is to always live below your means.
We often discussed finances with our children and as soon as they were old enough for pocket money we encouraged saving.
Dickens explained it clearly:
“Annual income twenty pounds, annual expenditure nineteen nineteen and six , result happiness.
Annual income twenty pounds, annual expenditure twenty pounds ought and six, result misery”
Whatever her income, it’s useful for her to think of the concept ‘pay yourself first’, i.e. before any other expenditure invest in your future self, whether that be in a pension, long term savings for a house deposit, or short term savings for passing the driving test. First thing to save for is an emergency fund of at least 3 months income in an easy access account in case of job loss (not in case of emergency trip to Ibiza with mates 😁)
Encourage forward planning; put away monthly sums for annual expenses, e.g. car tax, insurance, Christmas. I know people who are still surprised by the costs of Christmas!
Definitely put away a minimum of 20% of any self employed earnings for tax and NI bills in the future; I usually had a nice windfall after paying my tax bill as I didn’t earn loads and 20% was enough. Obviously if earnings are higher at least 25% would be needed. Depends on tax code and tax rates at the time.
Once pension, savings, and annual expenses are sorted, then look at things like holidays, clothes, haircuts etc. and budget a monthly sum for these. Again, they should not come as a surprise; look back at bank/credit card statements to see what has been spent on them in the past year and then divide by 12 for a rough idea of what to budget for each month.
The next item is monthly expenses; once you have your own home things like council tax, utilities etc, but for a teenager/young person living at home it might be a mobile bill or gym membership.
Then, and only then, you can spend what is left! If there is nothing left, then a) something needs to be cut back or b) you need to increase income.
On the issue of pensions, once in a scheme that has employer contributions then definitely pay in up to the amount matched by the employer, but if she is planning on some form of self employment in the future, then opening a low cost SIPP is a good idea, even if she only puts a small amount a month in. I use AJ Bell but it’s worth looking on MSE for suggestions. A world tracker fund with low charges is something to consider for investment, and yes HMRC give you tax relief direct into your SIPP. Having more than one pension is absolutely fine.
I’m now retired and not earning but still put £2880 into my SIPP every tax year, and get tax relief of £720 paid straight into my SIPP from HMRC.
I have repeated some of the good advice given by other posters, and this isn’t the definitive guide to finance by any means, but it should be a good start.
A simple spreadsheet is a good place to start budgeting, no fancy software needed, but some bank apps now have quite good budgeting capabilities.
As to my children; one took it all to heart and is very financially comfortable, the other not so much! You can lead a horse to water...