Until you become a series specialist, I would not spend the money to get your own coins slabbed. You will typically find most attractive mint state coins will grade out between MS-63 and MS-65. A novice in a series can usually understand that range of grades. A specialist who really knows the features of the design and where to look for problems will fair much better. They key is to expose yourself to as many of the type of coin you can and to learn patterns of wear and strike.
Washington quarters are fun- but they are common below MS-66 for most dates. Finding an MS-66+ or higher coin is tough- but knowing one when you see it requires lots of practice and experience.