*Slight* tough love if that's okay:
Your grades are what they are. You have a solid B in the sciences which means you can learn them to a satisfactory degree. Honestly, I'd focus on the MCAT and ECs and framing/nailing your narrative. This is about to be a long post so bear with me:
MCAT
You know that you're shooting for a 510 or above on the MCAT. It's doable you just have to consistently and faithfully study for 3-6 months. A 500 (aka you scored at the same as 50% of the individuals who took the test) makes me think your fundamental foundation for the subjects has holes in it. This theory is further corroborated by that 3.0 science GPA. You need go slowly and deeply and make sure you understand chem and bio and then move on to biochem and phys and finally psych/soc. I recommend a course like TPR only because they give you 6+ practice exams, it makes you keep a study schedule and you have a tutor there to answer questions about material you're not getting. I also recommend Youtube channels like Amoeba sisters and Crash Course. They may seem a little campy or *gasp* elementary but sometimes you need something super simple to hammer in the basics. I felt a little silly at first using the channels like this and then basically said "**** my self-consciousness, I need to learn this and deeply understand it anyway I can." Once your base is solid it gets much easier to study and retain all the material necessary. You also need to block of a day every week where you can train your brain and body to sit and perform for 8 hours. After you feel like you've filled the gaps in knowledge do as many practice tests as consistently as you can. If you sign up for a test on a Saturday then every saturday for at least a month you should be waking up and taking the test in the real conditions i.e. starting at 8am ending at 3PM. The test is literally half stamina. I was half asleep during the first section because I couldn't sleep the night before and it was my worst section because I didn't "click in" and get going until 15 minutes after the section started. You can crush the MCAT but you have to dig deep and get to
work
ECs
You said you had "decent" ECs and I'm not really sure what that means. If it means you're a part time scribe or you shadowed 1 doc for a month and nothing else that means that while they are decent they are also average. You cannot afford to be average. Your stats aren't superstar stats (neither were mine just FYI) so that means other stuff in your app must be superstar. You need to find something out of the box that allows you patient contact and you need to show longevity. I'm talking at least a year in the same position seeing the same patients and same colleagues. You also need to do some volunteering that may or may not be related to medicine. I've learned that med schools love, and I mean
LOVE when you can talk about an altruistic experience that you did because you're an altruistic person and
NOT because you are applying to med school. You also need to find a way to get some FaceTime with at leasts 3 docs in different specialities to show you've explored different sides of medicine. (If one of said docs can write you a LOR even better!). I totally understand that we all have bills to pay and need paying jobs, but you have to somehow find 3-6 hours a week in your life to do something out of the box to make your app pop out.
Personal statement/narrative
Your essays must be compelling. Again, because you're not a 4.0/520 app you can't say "I love medicine because I want to help others especially the underserved." You need to convey that sentiment while also drawing in the adcom with your story whatever that may be. If you still have access to your school's pre-med counseling services ask if there is a writing center that can help you with your essays. Your essays need to grab their attention and make them fight to bring you in. Be realistic with yourself, if you don't write well find someone who does and ask them to assist you as you craft each of the secondary essays and your PS.
If you want to do GPA repair that's fine but be cautious because unless you do remarkably better it won't make that much difference in an adcom member's eyes. Get that MCAT up, find some out of the box/epic volunteer position and stay in it for at least 9 months, (but really try to get 1 year) make sure you've shadowed 3 docs in different specialties, craft a compelling PS/secondary essays.
bada boom, bada bing, get some interviews (or just 1!), get into med school, pop that champagne, become a doc.
Sorry for the long post y'all! Good Luck
@azolesoul !