Also adding my +1 here. I've been managing upper 5 figures for a few years on some of the most competitive keywords. My process is pretty similar except I basically swear by BMM (broad-match-modified: +car +accident +lawsuit) keywords only and then the ones that perform exceptionally well I might convert or add an exact match but I can typically fly solely by an entire mix of BMM + negative keywords. This keeps it much tighter and less likely to trip up on wasted spend as all search terms will be close.

Bidding strategy is also incredibly important, as good as Google is getting their recommendation on overall strategy isn't great. Manual CPC (enhanced) has yielded much better conversions and cost per conversion compared to any other strategy. Manually adjusting each keyword, admittingly this does take some time but you set an overall max CPC and then increment where needed. Of course, this can be industry-specific and dependent on your goals. There are also a few scripts I run to automate some tedious things but that's less important.

Like ericabiz I also tried hiring on a few consultants hourly and it's been hit or miss but there were some insights I missed, so potentially worth it. Do not outsource to an agency, they are not worth the money. You need to groom your campaigns over-time and be dedicated. Use that extra cash on bidding for the ads themselves not the overhead of an agency.

You don't know what you don't know. Always be A/B testing.