Here's a few ideas of cosplays that always get a lot of attention at cons, and aren't incredibly difficult to put together!
Pokemon Come to Life
Strange as it may sound, these are like ridiculously popular (I mean, everyone loves or knows Pokemon) and not usually that hard to put together.
If you have a lot of muscles, I suggest something like PokeBro, or, if you have a few friends, try to put together a Diglet trio! Other popular ones would be Ashe or Misty, or you can do something like this buff guy that will make everyone laugh! Or, a rocket grunt! I personally think being Serena from XY is a really cute option that's made out of items you can buy at the mall.
Just somehow incorporate a Pokeball so everyone knows what you are and they'll love it!
The best kind of simple cosplays are the ones that make people laugh!! If you just throw together a basic Navi costume like any one of these, and make sure you have the ever necessary "HEY....LISTEN" sign, you'll be good to go!
Fry & Bender
I mean....who doesn't love these guys? Not super hard to put something recognizable together, and you'll appeal to a lot of different kinds of fans since Futurama is loved by a lot of different kinds of people regardless of their taste in anime.
Obviously there is a spectrum of different levels of commitment to the Bender cosplay (see above) but Fry is a pretty good bet regardless of how much you want to try/spend!
There's a lot of Doctors and companions to choose from--pick your favorite, make the out fit come together (Good will is your friend in this case!) and boom! Instant success :)
If you are into any of these characters, good luck putting it together, and don't forget to share your pics/progress/life points with us :)
The great thing about these is that even those that are NOT super dedicated anime fans (and there's a lot of these at cons!), they will recognize them, as they come from other pop culture shows and games!