This is the real-world, short & dirty way, as I have been told-

Don't bother with patenting at all first.
Basically you just start making and selling it.

If anyone contacts you and asserts a patent right, you then ask for 4-6 months of time to research their patent claim, and you see a patent attorney and ask what it would cost to to do a prior art search. Obviously you have to balance the cost of the search against the profits you have been making. The reason they have for allowing you this much time is that you offer to settle out of court if you cannot find anything to challenge the patent with. Also--moving against you legally would take a few months anyway.

Assuming you choose to pay the attorney and he finds prior art, you tell the other company that you have found prior art and they'll have to take you to court to get anything.

If he doesn't find prior art, then you offer to settle for 1/4th what your after-tax profits have been. Otherwise, tell them that they'll have to take you to court for anything more.

You can also offer to do some kind of a deal, a royalty fee or whatever, but be sure to stipulate that it's only valid as long as they hold the patent claim.

--------

There's four things to remember here:

The first thing is that a great many inventions simply aren't worth patenting, and never ever amounted to much more than the applications they were submitted on. Most things invented aren't useful or economical enough, and a patent doesn't guarantee nobody will infringe anyway. It's just a pretense to sue, and the profits of most small-time inventions don't amount to enough to justify waging legal battles over.This is the reason you don't immediately patent everything you think of: most of it will turn out to be worthless, and the process of obtaining patents isn't free.

The second is that nowadays--small-scale manufacturing really doesn't pay much (or for very long!) and nobody wants to take anything into court, because that often turns into empty victories--where a claimant can "win" the case, but the legal cost of the case is several years worth of profit that they would have made on the item in question. .....If you read about patent lawsuits much, you see this story over and over again--an inventor makes a few hundred grand on an invention, and then they see cheaper imported examples coming in. So they grab a lawyer and run into court,,,,,, and run up several hundred thousand dollars of legal bills. In these cases, justice costs money and whoever can show up with the bigger pile of money has the odds greatly in their favor.

The third is that if someone with a patent takes you to court and you break their patent, it's broken from then on. They can't claim it against you, or anyone else, ever again. So a lot of people with shaky patent claims aren't exactly excited at the thought of being taken into court, and are willing to make a deal to avoid it. (This is also why if you make a royalty deal with them, it needs to be conditional upon their holding the patent--because if that patent gets turned over by anyone else, you don't want to have to keep paying that company for a patent that they no longer hold)

The fourth thing to remember is that China Rules All.
If a Chinese factory decides to copy your -whatever-, the game is basically over. You (assuming you are not a Chinese national yourself) usually cannot reach them legally inside China, and trying to prohibit their products from being imported elsewhere at the container port is just a waste of your money and time. This is why you do not wait for anything, you have to produce & sell as fast as you can--because when the Chinese pirates get into the game, that means it is time for you to get out. Whatever it is, they can make it ten times faster and sell it for one-fourth the price, and there is no point in trying to compete with that. Lots and lots of people have already found out the hard way that it almost never ends in your favor.
There is one exception to this:
IF you are already having it produced in China and it is selling particularly well, then you can get with your Chinese production people and discuss the possibility of them taking the issue to court on their end. The Chinese manufacturer company can challenge another in court, and stands a good chance of winning. If you (as a foreign national) try to do it however, you probably will not.
~