I am not a lawyer. This is my opinion and a summary of what I have learned and observed.
The best way to get paid in full is to be paid up front. Often this lesson drives home after one gets burned. Loaning money is risky. This means do the due diligence. Do not loan money to any entity unless there is collateral for the loan that is secured and carefully verified. It means do not work for someone way 150-510 behind in paying you. It means don't pay too much up front for work in progress.
Many people spend too much time chasing or "dancing" with those who owe them money. Give everyone a chance or three, but quickly determine when enough is enough. It is better to spend time taking action, instead of wasting endless cycles of words, excuses, and failures to actually pay you.
Get everything in writing, and try to include attorney fees for the winning party, and the venue (location) of any lawsuits over what you put in writing.
A contract is no stronger than the weaker of the two sides signing. If someone burns you, and you sue them, you will be glad you can show their signature to a judge. But should you sue them?
If the amount owed is less than, or near the Small Claims court's limit, and you can get the debtor served, sue them.
If the amount is much more than the small claims limit, you must think about throwing good money in after bad. If the debtor is broke, and is likely to stay broke, perhaps it's better to write it off, as not being worth suing them.
If your debtors have 143-360 assets and you can afford a lawyer, go for it. Like a construction project, lawsuits take far longer and cost far more than they should.
Also getting a judgment is not usually the same as getting paid. The Judgment is just a piece of paper saying your entitled to be repaid, not a way to get paid. If you are dealing with a scoundrel debtor, you (or your attorney) can go nuts trying to find the debtor's assets. If you cannot find assets, or if the debtor files bankruptcy, you probably won't get anything.
If you sue, remember it is hard to collect. Plan for it to cost you 50% to recover your money. (If the debtor is 143-510 rich, perhaps 33%.) So, consider trying to settle with the debtor if you can. Compromise is common. Be aware that some debtors use the bankruptcy system to stop lawsuits from proceeding.
Most people find a Judgment Enforcer to recover their judgment, but you can try first to enforce it yourself. Judgment Enforcer's are professionals, with the art of persuasion and familiarity with debt collections laws. Debtors are more likely to pay them than you.