My Suggestion is what I practice now Prevention is the key: It's better to prevent something from happening, than having to fix it once it has already happened.  And what I ​mean by this is once people have already received your product or service, and haven't paid you for that product or service; 9 times out of 10, you will probably never get the payment for it.  So this is why I ​always charge for my service upfront & collect before the service is given; that way I don't have to deal with chasing dishonest people to get my money.

One tactic I have used over the years is to notify another entity. There was the time an ad agency had placed a series of ads and then failed to pay for them, so I notified the actual client. In another situation, I told a contact with another business (which I knew the party did a lot of business with) to "watch out" for them, only to receive the Past Due check 3 days later. In other words, do something to make it known that you aren't keeping this a "secret" that they are delinquent.

Being a solo business owner I had to know my value and price my coaching to match my expertise and have found I attract clients who value what I do. Many coaches sell themselves short and discount because they don’t believe how valued they are with what they have to offer. Confidence in yourself and your business is so important😁

Getting paid upfront or collecting %'s as you go can be very effective.  Some of us can not request a full payment upfront, as that's not traditionally how our business works. No matter what, there will still be that rare one that slips through the cracks but you can minimize it and only loose a little, not everything.  Collection agencies and lawsuits do work but they take a cut and if the amount lost is small it may not be worth it to pursue.   

I had a local client who tried to stiff us. We gave him 4 months of notices and calls, then a final warning. Turned off his services (which was his business website and card processing), reported him to the BBB, Duns and Bradstreet, Google Reviews, and our local chamber of commerce. Ultimately its business. He went to extraordinary lengths to not pay while still using services for 4 months.

A)  You must use a contract both parties signed, dated, and detailing the service and the payments made. I use a 1/3, 1/3, and 1/3 (or 50/25/25) payment schedule. 1/3 before the project begins, a 1/3 after at least 50% completed, and after the job has been completed. Make sure they sign an approval of the job statement. 
​If they don't pay after 30 days (with weekly reminders), hire a collection agency. Tell them by not paying it may impact their credit score. This will only work with a signed contract. Verbal agreements are worth the paper they are printed on.
​B)  If you didn't execute a signed contract, have a really large man ring their doorbell after dinner time, and without threats, have him ask for your payment. Have him take a receipt for the payment if made.
You'll have to pay your collection guy for each visit (every week is recommended), but I have had very good results using this idea.
If a business does not pay, file a complaint with the BBB; it's free. I tell them I will be doing this and then remind them the complaint stays on the BBB's website forever.
​​Good Luck

I have sent letters to remind them of payment. I send one letter per month. After the 3rd month, I threaten them with Small Claims court. It works all the time. They send the money.

We do hlf down to begin the process. The other hlf is due after approval of their design. We won't cut the stone unless we have all the money in house. Had too many issues in the past. 

What to they get for free from you?

Are you a B to B or a B to C?