There have been way too many non-pay threads on this forum lately asking for advice on collecting payment after the fact. The non-pay problem can be solved by simply doing your "homework" BEFORE you do a speck of work for any company. Especially the companies that you have never met in person. We personally do not work for anyone that we have not met in person and have also researched their company. Additionally, we do not bid or accept a job that we have not personally visited BEFORE we bid the job. You might say it costs money and time to do a pre-bid visit but it takes more time, more effort and more money to do a job and not get paid or find out the scope of work is way different than you had anticipated.
Further, it helps getting paid if you have a good working relationship with the person responsible for accounts payable. You need to keep this person on your good side. A lot of companies have specific billing formats. Most will not pay you if you don’t follow their format. Make sure you understand their billing format and the required data that must be attached to the billing, BEFORE you start any job. It will save you time if you know what data to collect while you are at the job site. There is no money in going back.
Don't fall for "the checks in the mail" routine. All our contracts are written with a 30 day payment due from the date of invoice. We are calling them if we have not received payment in 45 days. If a company does not have the wherewithal to make payment on our schedule, we move on to a company who does. We do not accept or bid any jobs that have ridiculous payment lead times of over 45 days.
Bottom line is, DO YOUR HOMEWORK BEFORE YOU DO ANYTHING ELSE! It will be worth your time.