When looking to hire a professional brick paver sealer, you should always look for a company that has insurance and can provide you with references. The internet is a great way to find out the proper way to apply paver sealer and just by asking the potential contractor a few simple questions about it , can help you make a decision whether or not to hire them or not. Print off a few pages from experienced brick sealers that have laid out every step and if the company that you are interviewing does not explain his method of applying the sealer to you that even half way sounds like what you have read then a big red flag should go up and you might want to consider moving on to the next guy. If a potential company that you are thinking of contacting has a website then look through it and see if they have pictures of past jobs. Asking them when you call to set up the estimate if all the pictures on their site are of their own work and not just examples of what their work may look like is a very good question. Putting up websites and using other companies pictures and words is not unheard of these days. This is where the references can really come into play. If the contractor is insured, you have spoken with a few past clients about their ability to apply paver sealer properly and they get an overall good rating, then they should be considered for hiring.