Hey David,
Firstly, welcome to the world of SEO.
I know that things can seem pretty confusing and daunting, especially when your new to SEO. The key is to not rush into any decisions without having evidence to back the potential benefits. It's very easy to go storming into things and end up making poor decisions. Here is my recommendation for how to proceed from here:
Step 1:
Benchmark your current rankings, traffic etc. (You need to do this so you know if the changes you have made have had a positive or negative impact)
Step 2:
Do a quick health check of your website. Use Google Webmasters to check for any issues or penalties you may have received. Fix any issues as soon as possible.
Step 3:
Do a backlink audit using Open Site Explorer. Export your results to Excel and then analyse them. Look at every single URL and check to make sure that they're not harming your site. If you find any that you think may be harming your site, then get in touch with the webmaster of that site and request them to remove the link. If that doesn't work, use Google Disavow Tool to remove it. This article on Link Audit Guide For Effective Link Removals & Risk Mitigation will guide you through this process.
Step 4:
Use Open Site Explorer to analyse your competitors backlink structure. Look at the places they have obtained high quality links and attempt to target those same sites.
Step 5:
Once you have successfully obtained backlinks, analyse the results against the initial benchmark you did. Then you can see exactly what has improved and other areas that may still need work.
The above is a time consuming process and takes patience. Seriously though, it's worth doing it right as this will help prevent dips in traffic in the future.
Hope this is clear and concise enough.
Let me know if you need anything else explained.
SilverDoor