I'm obsessed with them :) The quickest way to make a fun nail design is to add polka dots. I have come across some awesome ways to make them even and easy to do. First off you can buy a dotting tool from a beauty supply store. The main benefit is that they are sturdy and come in MANY different sizes. Plus the handles are generally very pretty.
I don't have one of these mainly because I see no reason in paying for one when you can make one at home just as easy. I have come across 3 ways to do polka dots each with pros and cons. I'll start with the cheapest.
This is something you always have around you house. They are inexpensive and disposable which is great if you do a lot of nail designs. Really nice for multiple color designs because you can toss it instead of cleaning it off. The con would be the size of the dot. You either get a tiny dot or the dot is big but has wayy too much polish. If you are like me you hate waiting for polish to dry and a thick dot will take a very long time to dry. If you are just starting out though these are great. They definitely can work for more intricate designs that require a small tool though :) Plus remember things like toothpicks that are square shaped can make fun designs.
End of a paintbrush
While you may not have one at home they are inexpensive also. These make consistent sized dots and are very easy to hold in your hand. One big con is the type of brush. Do not buy brushes with painted wooden handles. When you go to clean them off and start a new set of dots the paint will come off in the polish. I have some with red handles and I would get red spotted dots but not in a good way. I suggest the super cheap ones for kids. You can get different sized handles and do fun dot designs.
My Absolute Favorite
This is the hands down best way to make polka dots. It is so easy because you hold it just like a pencil and it is much more left hand friendly (with practice). It makes consistent sized dots and it can be cleaned so easily. Just dip the end and it's perfect. Extra tip - for huge dots use the eraser end :). The con is that you lose a pencil. The polish will get inside the lead barrel and ruin the pencil. But I mean they aren't that expensive. Just pick a color you don't like and use that one. My favorite are BIC pencils because they have a rounded but blunt end. Don't forget to remove the lead so you don't waste it. You can also check out different sized pencils to get various dot sizes.
I always paint a base color so that the dots show up better. A fun way is to paint each nail a different bright color. It will look super scary but the dots tone down the colors a lot. I do this more for toe nails because it is more work and it stays on longer. For fingernails I paint one color or I alternate nails (especially for holidays) Just like I did for my Halloween look at the bottom of the page. I let the color(s) dry very well. If the base color is still wet and you dot on top of it with too much pressure the colors will mix and make it very messy. Once the base coat is dry I put a few dabs of polish on the front of a magazine. The glossy cover makes the polish get onto the tool well plus it is a great way to recycle them. After each look tear off the page and use the next one. Just make sure you remember it has wet polish and don't stick your hand in it. I then use whatever tool and begin dotting. Spacing the dots so they don't look planned just takes practice. If it helps look at someone else's picture and match the locations they use. In time you will get used to how to space them out. Once you are done either toss the toothpick or clean off your tool. Then let your nails dry for a while. The dots can have many layers of polish and if you mess them up they will flatten out and look very crappy. The key to polka dots is to keep them clean and defined. By all means use a good top coat. I recommend Seche Vite, totally worth the cost. I hope this helps and gives you some fun polish ideas. Last hint - glitter dots can look very pretty mixed in with the white dots :) Also you don't have to put dots over the whole nail. A diagonal line of dots can be very pretty.