1: If you're making the kind of cake pops that are baked cake mixed with icing like I did (not baked in a special pan), make sure you refrigerate and preferably freeze your pops (with stick already in them!) before dipping them. Only take some out at a time to dip, they should be as cold as possible so they stay solid in the hot coating and don't leave crumbs in your chocolate.
2. Make sure your chocolate is deep enough to cover the entire cake ball easily, including where the cake pop and the stick meet. You will probably end up with extra melted chocolate when you're done and that's better than making crappy cake pops, so just roll with it even if you're a "waste-not/want-not" fanatic like me.
3. When you dip the cake pops, lift them out of the chocolate by using a fork to scoop them out. No one will see the bottom and it is just one more thing preventing them from falling off of the stick.
4. The chocolate will set quickly after they are dipped, because the cake pops are cold! Add your sprinkles etc quickly after dipping them. You can dip oreos in the leftover chocolate and they'll be more forgiving.
Some general chocolate dipping tips:
A double boiler will always work best. If you don't have one, just lay a tight fitting glass bowl over the top of a saucepan.
Chocolate with a higher percentage of cocoa solids will melt at a lower temperature and be easier to keep at an even consistency. Conversely, chocolate with a higher percentage of cocoa (i.e. the dark chocolate bars that boast things like 65% cacao) will melt poorly and burn easily. Use a creamy milk chocolate for best dipping results, or semi-sweet baking chips if you want a "dark chocolate" coating (since they're made to melt in cookies). My favorite bars of chocolate to dip in are Hershey's Symphony bars.
An easy thing to use if you're dipping in chocolate for the first time is the "candy coating" you can find in the baking isle.
When chocolate goes from melty and smooth to crunchy and starts getting solid again, it is called "seizing." Any addition of water or cold milk will cause your chocolate to seize. If it starts to happen, try adding a little bit of vegetable oil and mixing well. (If I were melting most of a 12 oz bag of chocolate chips and they began to seize, I would add about 2 Tbs of oil and mix).
We liked chocolate cake mixed with chocolate icing and dipped in white chocolate the best, it was very "cookies and cream." I was shocked when I tried these and found that one box mix of cake and one store bought icing container made 50 cake pops! Nom nom nom. Happy Dipping!