Aside from being visually appealing, a watch should be looked at as a quality timepiece that might be handed down through generations. It might also be considered an investment(although certain factors have to be at play for this). When purchasing a watch consider what you will be using it for. Casual wear(a sports watch for example), business(something more formal or thin that would not interfere with a dress shirt). Perhaps a dual-time for those who travel a lot... you get the idea. There are many quality watches out there that will last a lifetime with proper care. Crystals come in three flavors with varying degrees of hardness rated on a scale from 1 through 10 with ten being the hardest(diamonds)... (1)Acrylic, (3)Mineral, & (9)Sapphire,the latter being your most durable offering superior scratch resistance, but it will cost you more. Even though a sapphire crystal is almost as hard as a diamond, it is not shatter proof... on the contrary, sapphire crystals are more brittle than mineral crystals & will therefore shatter more readily than mineral crystals. The advantage to sapphire is scratch resistance not to mention it is simply more esoteric. Finer watches will usually offer Sapphire crystals. Watches with exhibition backs may not necessarily have a Sapphire crystal on the back. The reasoning is that the back isn't exposed & therefore is protected). Water resistance to varying degrees(unless you plan on diving or being around water) isn't that critical but is usually a sign of greater durability. Screw down crowns add to the water resistance of a watch. Be aware of the fact that the water resistance can deteriorate over time through climate & age(gaskets can & do become brittle & lose their ability to seal effectively). Also consider the fact that eventually you'll have to replace the battery. Once the seal is compromised you'll have to re-establish the seal by replacing the gaskets.The metals used for the case & bracelet should be an important consideration as well as the movement(quartz, automatic & manual). Automatics are mechanical watches with a rotor that powers the mainspring through wrist movement. Although automatics are considered more collectible & more esoteric in the watch world, they are not as accurate as quartz movements. Here again, for the discerning watch collector, the issue over watch accuracy in automatics can be circumvented by purchasing watches that display the statement(on the dial face), "officially certified chronometer", not to be confused with "chronograph". This guarantees that the movement is of the highest quality & has been refined & honed to the highest standards. This translates into a watch that will be almost as accurate if not as accurate as any quartz movement available. The better the movement the more accuracy in the time displayed. Quartz  usually offers the most accuracy but even here you will find varying degrees of quartz quality & tolerances. Once again, a better watch will offer a better quartz movement. Most Japanese watches offer fine quality as do Swiss but in my opinion if you are collecting watches as an investment, you have to consider the intrinsic value that a Swiss timepiece offers.  There has recently been a proliferation of Chinese watches or famous brands using Chinese movements(cost cutting measures). Although some of them seem to be of good quality, I still feel that the old caveat should be taken into consideration... "let the buyer beware". A totally Swiss made watch will state(usually on the dial)"Swiss Made"and consist of at least 50% Swiss parts to qualify. If it states "Swiss Movement" this is an indication that the movement is Swiss with the assembly done elsewhere. "Swiss Parts" means just that... no part of the watch was assembled in Switzerland. Seiko, Citizen, Pulsar, & Orient make fine watches for the money, but be careful of cheap imitations(this also holds true for Swiss timepieces). Seiko offers Quartz & Kinetic(Quartz with a rotor that powers the electronics within the timepiece rather than a mainspring). Citizen offers "Eco-Drives"(powered by light). Elgin offers PQS(again, this is powered by light). Orient is known for "Automatics" utilizing a Myota movement. The Myota movement is well known for its durability. Pulsar is owned by Seiko & also makes a fine watch at a lower price point. There are many fine Swiss watches on the market with a wide price range. Some of the more common names are Movado, ESQ(owned by Movado), Rotary, Tissot, Accutron, etc. Some of the more esoteric names are Raymond Weil, Rolex, Breitling, Corum, Concord, Patek Phillipe, Zenith, etc. Prices for Swiss made watches can range anywhere from $100 to  many thousands of dollars. Always keep in mind that if it sounds to good to be true, it usually is just that. If you're looking for a Rolex for example, be prepared to pay thousands. If someone is selling a Rolex for a few hundred dollars, walk away, no, run away, because either this is a fake, or it's hot. There are many websites devoted to helping you identify fakes. You should take the time to investigate these sites & become knowledgeable. Remember, it's your money. Additionally, stay away from "hot" watches. In essence, by buying hot watches, you're supporting an illegal trade. Also consider where they've come from... that's right, someone's home or business. It could even be you someday! Always support the retailer or e-tailer when making a purchase. You'll be buying a watch that's legit & have recourse in the event there is a problem. I must mention that you can purchase a watch for as little as $10. Remember, these are of poor quality & generally will not last more than a year or so. You could consider these to be "throw-away" watches(since the battery replacement usually will cost more than a replacement watch of the same quality).The thing to remember is that all watches will keep time. Therefore,  any watch up to $100 is for keeping time... above $100 it becomes a statement. A perfect example of what I'm trying to say is this, " a Yugo will get you to your destination as well as a Mercedes"... the Yugo is purely utilitarian & the Mercedes is pure luxury. It simply becomes a question of "how" you want to arrive & "how" you would like people to perceive you. Bracelets are important and should offer solid end-links with quality clasps(double -deployment or something similar). Leather bands are fine but don't hold up to outdoor weather conditions such as rain, etc. so if you work outdoors or find yourself outdoors often a metal or rubber bracelet would probably be more suitable. Watches are also made with differing metals such as: stainless steel, titanium, ceramic, tungsten, carbon composites, platinum & gold. Of course gold & platinum would be the most costly. Typically a high-quality stainless steel case & bracelet made with 316L surgical steel is highly durable but would also weigh substantially more than titanium(the downside with titanium is poor scratch resistance). Watches also come with differing dials & offer various complications within the dial face(subdials referring to chronographs or second hands placed within a separate/smaller dial are more difficult to produce & typically will cost more). Casebacks will be "snap-off/pop-off", "screw-down" or "screw-in". If you're inclined to purchase a 2-tone watch consider that they are not all finished to the same degree of quality nor do they all offer the same amount of gold layering. Typically watches that specify gold layering will be about 3-microns, some will offer 5-microns. Your better watches will offer 10 to 20 microns of layering. Also be aware of how the gold is applied(electro-plating being the best & will withstand a lot of use without showing signs of ware on the finish. There are still other factors to consider before buying a watch but hopefully this abbreviated guide will help you get started in making an educated decision on purchasing a timepiece. Have fun collecting watches & appreciate the craftsmanship that goes into the making of a fine watch... it is truly an art!!!