Really depends on what you are looking for. Are you interested in Pro-Staff or field testing?
Field testing is where they send you products to test, utilize and evaluate. Some of them simply want to know if they work, what you like or didn't like, what you caught, and so on. Others want hard information. Does it work, does it break, does it perform well, what would you change, and so on. Some don't always want to hear the answers to the questions. Be prepared to write product evaluations and or testimonials.
Pro-staff is a little bit different. Different companies have different versions and "definitions" of what pro-staff is. Here is my definition: Being a pro-staffer for a company means that you will represent that company for some form of compensation. Either by way of payment (hard money) for the usage of their products. Payment for the purpose of promoting their product IE, decals on the side of your boat, truck, wearing t-shirts, and so on (also called advertising). Or payment by way of providing products free of charge (up to a certain dollar value) or products at a significant discount.
IF (capitalitzed) you utilize products from a company regularly, the form of a discount may be your best bet. You use them all the time, they are throw away items, and you normally purchase them anyways. Best bet is to get them cheaper than you normally purchase them. Free products is also great IF (capitalized) you use that product all the time.
Free products are always great IF (capitalized) you use them, are confident in them, and like the product. Getting them for the soul purpose of getting them doesn't work. There isn't a value to you or to the company. In other words, if you would never purchase the product outright, you probably don't want to advertise for them.
The worst, and I mean worst one to get in to is the one where They offer you a significant discount to solely use something you don't alreay use. I know of a guy that was first getting started. He was talking with a rod company and they offered a significant discount to him if he would use their products. He was so wrapped up in the fact that they wanted him to use their products he lost sight of his intent. He purchased the product (fishing rods) at a significant discount. Unfortunately, they had a minimum order amount. He ended up spending $600.00 on fishing rods he had never used (9 in total). After the first weekend, he had broken four of the rods. He called the guy back and they said they could replace them but he would have to pay a fee. In the end they got $600 dollars out of him. Sure, it was less than what they normally would have gotten for those 9 rods (which were junk) but they got money.
If it is solely for tournament fishing and you are looking to represent a company (you represent them) I suggest becoming a member of the NPAA (National Professional Angler Association).
Any questions, shoot me a PM and I would be glad to answer them the best that I can. I represent companies in several ways. Some of them I am paid to advertise for them. Some of them I get free products, and some of them I get reduction in cost on products. The are ALL (capitalized) companies that I used prior to representing them and would continue to use them even if I was not getting compensated. Too many guys sell out just to make a buck. I also represent local companies (not in the fishing industry). They compensate me for the usage of space (advertising) on the side of my boat, motor, trailer, and all fishing related gear.
I have OCD "Obsessive Crappie Disorder"