The advantage of doing a patent search is that you may find that your invention or something very close to it has been filed already, saving you thousands in patent and attorney fees. The disadvantage is that it is generally incomplete, as there is no visibility into unpublished patent applications, which in the US pertains to most patent applications less than 18 months old.
It is generally recommended that one do a search if one is not familiar with the general subject matter. For instance, if the inventor has been involved with research and development in his field for many years, it is likely that he knows whether or not his approach is a novel one. But if one came up with an idea in a flash and has little or no visibility into the broader subject matter, it is a good idea to do a search as discussed on https://inspirationfeed.com/inventhelp/.
Filing provisional patents will set you up early in the patent process, but will also delay the USPTO from even queueing up your application for examination until a utility patent is filed. At the end of the 12 months you must make a decision as to whether you want US or you want to seek multi-national rights to attach to your application.
Filing a utility patent immediately gets you into the queue for examination, is a bit more expensive and requires more work on the part of the attorney or and patenting agency, such as InventHelp. However, it then gives you the same 12 months you would have had to decide whether you want just US or multi-national rights.
Filing a PCT application gives you about 30 months from the earliest filing date of the application to decide what countries you want to file in (30 months if a PCT is filed first, 18 months if it is filed after filing a utility or provisional patent). If you only wish to file in a few countries and you know that, you might be better off filing in those countries directly. For instance, the cost of patent office fees for filing the PCT application alone is about $3000-$5000.