Congratulations, changes your life, driving does.

1. Change all your fluids, Oil + filter, flush the radiator, do a 4x drain and fill on the transmission. So, drain the pan, fill with new fluid equivalent to what's come out. Take her for a spin, get it warmed up. Drain and fill again. By the time you do this 4 times, you should have basically all brand new fluid in it.

2. Replace the cabin and engine air filters.

3. Buy a floor jack, always have a scissor jack in the back along with the spare. But keep a floor jack and a set of stands at home for when you need to work at home.

4. Do easy jobs yourself, firstly gaskets and seals as well. Valve cover gasket replacement kit is an easy job. You'll get a look at the valves then and you can see if you need to do a little engine flush. PCV valve can make a big difference too and that's usually very simple to get to.

5. Get someone who isn't mechanic looking to make a few quid about the state of your brakes. Pads and rotors are easy peasy stuff.

6. Buy a code reader, a decent one, or any bluetooth one that will let you read live data from the ecu. You probably won't need it now, but as you learn more your car and common issues, you'll want one to be able to give you a clue about why something is happening.

7. Get underneath and check the bushings on suspension parts, lower control arms, trailing arms. That stuff just goes one day. But, if you see a bushing is starting to tear, or seize. you can find the replacement part and avoid being stranded.

8. Because you're in the UK, get a few rebuild kits for alternators and a/c compressors. They are BIG TICKET items and they will fail on a 20 year old car. You can follow a guide to rebuilding them, replace brushes and seals and you'll save yourself £££££.

9. Look up community formus (not reddit) for your car specifically. They can be a big help in finding common issues and answering questions about maintenance and upgrades.

10. Check out Chris Fix's youtube channel, he's got very comprehensive guides from beginner stuff up to replacing internal engine components. Would recommend as someone who learned how to fix their car using Youtube.

First tip is to clean that giant piece of bubble gum off the front

Replace the cabin filter (10 minute job) with a carbon activated one. I find it makes a big difference on longer drives, otherwise my nose/throat are awful.
Don't worry about the ticking sound the engine makes when it's cold, that's normal.
Check what the tyres are like (age from the DOT code, and tread).
When you're feeling flush, I recommend getting all-season tyres, Goodyear Vector 4 have served me well.
Upgrading the speakers is not difficult, and makes a big difference. (At least under 50mph, lol). The door speakers need to be under a certain depth, or the windows won't go down.
If you want CarPlay/Android auto, the fitting kit for a standard 2-din unit is about £25, and a half-decent unit is about £200 (Sony xav-3250).

Imo, it's well worth getting some good cleaning supplies.
A good shampoo to get it clean (I like megiuars gold class), then a sealant to keep it clean longer (meguiars ultimate ~~sealant~~ wax, comes with applicators too).
Wash with the two bucket method, and a couple of microfibre mitts.

Get a dashcam as soon as you can reasonably afford one, and set it up.
I like the Viofo A129 duo, it's basically invisible behind the mirror.
Halfords have this one on special if you don't want to spend that much:

On the actual driving side, once you've had a bit of time getting used to driving, buy yourself a copy of Roadcraft, and have a good read through of the advanced techniques, particularly IPSGA, the Car Control system, and limit points.
Learn to drive defensively, and you'll avoid a lot of sticky situations entirely, rather than having to suddenly do things.
Sometimes, you just have to let dickhead drivers be dickheads: You may be in the right, but if you crash you're both in an accident.

A dashcam is always a good idea; it can quickly pay for itself when you're able to prove you weren't at fault for that parking lot fender bender.

Project Farm on Youtube did a comparison of a bunch of popular ones a month ago.

Read the owner's manual.

Don’t turn it into your mobile trash can

Speaking from experience: the gearbox is trash, don't get freaked out if you can't get it into reverse. Shift into a different gear and then try again. Other than that it's a great little car and has been super reliable. Happy driving!

If it's your first car, I'll assume that you're young(ish) and or an inexperienced driver. Please forgive the assumptions if they're wrong as the following is good advice for anyone.

Get yourself on an advanced drivers course. Many IAM local units used to do disounts for younger people, they may still do. They teach you to drive properly using the same system the emergency services use. Can save a massive hit on your insurance if you're involved in an accident.

I thought I was a good driver beforehand, but it taught me loads.

Do a good wash, and wax. Wax is a protective coating- do this every few months and it makes cleaning quick and easy, as well as protecting the paint. Every time you do it it's like putting money in the bank, a car with good paint looks like a nice car, and people pay more money for a nice car.

Buy a little bottle of rain-x. Read the instructions. Do them twice for the first go. It makes an insane difference for your vision when driving in the rain, and driving in the rain is when you really need to see.

Learn how to change a tyre before you need to do it. Figure out how the jack works, and where you need to put it under the car so you don't damage anything.

Don't trust your drunk self. The cost of a taxi home and back to your car the next day is way, way less than the cost of having to live with the fact that you are responsible for the death of someone's child. Don't give a shit if you feel fine. Give your keys to the barman if you when think you might try and drive.

Remember to have the oil changed on schedule. Does your car have a reminder light for this? Also keep an eye on the air in your tires. There’s usually a sticker on the inside driver side door frame that tells you what the inflation level should be while the tires are cold. Some cars also have a warning indicator to let you know when the air pressure in one or more tires is low.

Make sure you have a driving licence

Get an OBD2 adapter. If you're on Android, a cheap ELM327-clone with Bluetooth will do. If you're on iOS, you'll need one with WiFi. There are apps (Android: Torque Pro, iOS: OBD Fusion) to read out any error codes and they can also give you the values from all the different sensors. Helps a lot with troubleshooting.

I always change the cabin filter as that thing is always filthy. Apart from that just keep it clean and check it regularly.

If you drive drunk go as fast as you can to get off the road as quickly as possible

Remember to drive on the left side of the road. Unless you go abroad, then check.

Have a look at the maintenance schedule and see what needs doing. Seeing as 70.000 miles is equivalent to 100-120 k in metric, some things may need replacement. If the timing belt has not been replaced yet, it will probably have to be replaced at that mileage. If it actually still is the factory one, it would be very old and require you to act ASAP. Another thing is brakes and suspension. Seeing as you guys have regular MOT inspections however, major issues will have been noticed.

Other than that, you should check stuff like spark plugs and replace the engine and cabin air filters.

get a dashcam!