I am writing these articles on research and I keep hearing, "but Danni you just have an eye for that stuff". I want to assure you it isn't something that just occurred, I have worked at it! And if you are serious about selling fine antiques and collectibles you can too! I am going to share my process... and believe me it is a continuing one! I am far from an expert on things.
Ok First, pick an area to work on, say glass or pottery, or primitives... whatever you think you have a good resource for in your area.
Now go out and get your hands on as many IDENTIFIED pieces as possible. Notice I sort of hollered that word, because this is key! You are not going out to buy right now, you are on a research mission. Visit your local antique mall as you are sure to find a lot of cool items already tagged and priced. Zone in on your expertise of the day, let's say American Pottery. This will include makers such as Roseville, Weller, McCoy, California Pottery... you name it! Pick up and handle and inspect those pieces. Look at the workmanship, feel the weight and the way the glaze appears on those quality pieces. Most of them will have a maker's mark, but some does not, this is why it's important to learn the attributes of good pottery.
Ok now that you've played with the good stuff - visit a thrift store (now not sayin' thrift stores don't have good stuff) you will have an abundance of cheaply made, low end pottery to now pick up and compare... and if you are real lucky you may hit a piece you now know something about and it's value!
To hone your skills and "your eye", consistently put your hands on good quality pieces, I know many tend to not even look their way knowing they are expensive, but if you don't scrutinize them, you won't learn the differences that only come from experiencing them with all senses (ok maybe you shouldn't taste them).
Do this with any area of niche you want to go into, glass is a real good one because most of it is unmarked and if you can learn a certain maker's trademarks, that is something a lot of people know nothing about and won't touch! Finding the items that a dealer may or may not know much about can often score you a nice resale.