Hello,
There are many tools available to find out what keywords your competitors are paying for. My suggestion is to use SEMRUSH, as this will give you an idea of the most used keywords and the bids. Take into account that it is not 100% precise, so the best thing is to use this information to carry out your own tests and see which keywords perform better.
The best strategy is to have a landing page and an experience that users like: does the keyword math the intention of your website? Try to think like a user and give the user what hes looking for to reach high quality scores.
Looking at your website, it would make sense to use keywords such as 'outsource sales force' or 'increase sales' and keywords in that direction. Your service is extremely useful to any business.
Regards,