If you have a regular income, a weekly or monthly paycheck which you can continue to receive, consider to create a personal budget plan. It can be as sophisticated as an online or offline budget program, or as simple as a notebook to track income and expenses. This notebook can also be a spreadsheet in the program of your choice, which can simplify things if paper is not your "thing."
I would hesitate to recommend a specific program for your budget, as there are many variations, but the notebook concept is very easy to implement. I have been using this method in one form or another since the mid-70s and it's quite effective.
Create a list of your expected expenses. If you pay utilities, split them out by type (electricity, water, heating fuel, etc) or cluster them in one block if you wish. If you purchase groceries for home-cooking, create a category for this. If you have a motor vehicle, another category for fuel consumed and possibly another for scheduled maintenance.
Examine past statements for checking and credit cards to ensure that you collect as many categories as possible. Once you have these categories, assign a chronological period to each one. For example, you likely pay electrical utilities on a monthly basis. This entry could be 12 for 12 times a year, or 1/12 for the reciprocal calculations.
If you are paid on a weekly basis, your calculations would be different from bi-weekly or monthly income receipts.
The objective of this exercise is to determine how your expected income matches your expected expenses. As a reference, I would assign US$250 per month for electricity. This is $3000 per year. For a weekly income, you would want to assign (in the notebook/spreadsheet) about $60 per week. The math generated is $57.69, but by rounding up, you have an additional buffer to your budget. For a monthly income, the math is slightly different, but the results are the same. That one is certainly easier, as your assignment becomes $250 per paycheck.
For every category, perform the appropriate math and time reference. Sum them up for the pay period. If your have a higher expense than you have income, you are in trouble from the start.
Based on your description, you aren't that deep in trouble, but the above math will give you a good idea of your standing. In my younger years, I was able to determine that my weekly income balanced on my expected expenses provided me with more than fifty dollars per week spending money. I had a line-item for "spending money" and it was wonderful to see it climb each week that I restrained my spending.
At the time, I did not have a savings program line item, nor did I allot for vehicle service such as oil changes and valve adjustments (way-old air-cooled VW!) and had to shell out some of my spending money for a replacement engine.
By estimating your expenses high, you will have buffers for each category that will appear each time you pay one. For example, the $250 for electricity would have a deduction for a $210 payment, leaving a $40 surplus. Ideally, you keep the surplus in that category, but it also serves as an emergency resource should it be necessary to replace an engine.
On paper or in a spreadsheet, you keep a new page for each pay period, transferring the previous period's balances and reference figures, allowing you to know at a glance your financial status. As a young adult, my piece of paper fit in my wallet and was re-written on a weekly basis. No computers back then!
Regarding the interpersonal aspect of not "splashing money about," consider to inform anyone who asks that you have established a budget program and are unable to be quite as lavish as before.