Trying to upgrade my car s sound system but don't know where to start?

I have a 2015 Honda Accord Base and I want to upgrade my sound system but I have no idea where to begin, I don't even know if I want/need an amp, sub, or just new speakers. I don't want anything to crazy expensive, is it possible to upgrade my sound for less than $500? Maybe even $400? Any kind of information or advice would help!

Go to place that do systems n sterio not dealer

Crutchfield.com will have what you need, Alex.

Go to a car audio shop and they can show how to upgrade your car stereo.

Start with a set of speakers that sound better. Maybe the stock speakers sound good already but you want deeper bass for the effect. Listen to them in the shop before you buy them. Are you talking "better sound" or louder with deeper bass? Audition a subwoofer and discuss the installation in your car.

Replace the stock speakers first. That will give you the best bang for your buck.

Yes, it's possible to upgrade your system for less than $500. Like what the other man said, aftermarket speakers do NOT perform well on the stock HU.

Why? Because they lack producing an adequate frequency range and they only produce 10-20 watts. A lot of aftermarket 6.5 and 6x9 are design to perform well on 50-150 watts RMS.

Running high quality aftermarket equipment on the stock equipment is NOT the way of improving the sound system in your vehicle.

The problem with doing a basic upgrade (like just changing speakers) is you're still left with only the factory amplifier to power them.
Many aftermarket speakers are designed to perform optimally being driven with 50-100w rms of amplifier power. Running them with significantly less power may not allow them to perform much (or any) better than the stock speakers.

The info I found on a 2015 base accord is 160w am/fm/cd with 4 speakers. I'm GUESSING that means 160w max/peak, aka ~80w rms (or less) divided among the 4 speakers. So I'd figure on around 20w rms per speaker.

In order to make a worthwhile upgrade I would plan on a good pair of front speakers and an amp to run them. You can do rears too, but the majority of the sound should come from the front, so leaving the rears stock will save quite a bit of money w/o much (any) loss in sound quality.

A decent pair of 6.5's start at around $50. Entry level components will be $100+ if you want to go that route (usually better sound quality but a little harder to install)
You should be able to find a suitable amp for around $100.
Installation - I'd guess $100-200, maybe a little more for wiring and other accessories.

Physically mounting the speakers will be less of a hassle than getting the necessary wires ran.

Crutchfield is a good place to go for preliminary research.