After The Purchase
Once you've done all of your research and made the decision to make a purchase, there are several things that you should do right away to make sure that you're better covered down the road should some type of issue arise.
ALWAYS Keep Records and Receipts!
Anyone that has ever had to return an item to a store knows that the VAST majority of the time it is much easier if you have your receipt handy. The same can be said for any type of purchase.
Whether it's a single receipt or more involved paperwork/documentation for a more complex purchase, holding on to these records is always a good idea as they may be needed in the event that a problem surfaces with the product or service down the road. Make sure you store your receipts and other records in a safe place that you can easily access at a later time.
If the purchase involves a signed contract, such as a gym membership or home contractor etc., make sure you keep an original copy of the contract on file. This way, you have proof of what was originally agreed upon if you ever need to go back and reference it. Otherwise, it will be their word against yours should the scope of the deal even come into question.