I spent my time tonight getting things done in preparation for the Goldenrod Gym. First, I had to explore Goldenrod City itself, which took quite a while. Some of the things I did:
-I got the Bicycle and registered it right away
-I received the Coin Case and won a round of Voltorb Flip at the Game Corner
-In the underground path, I defeated a few trainers. Then, after obtaining several Accessories, I dressed up my Bayleef and took its picture.
-At the Radio Tower, I got the Radio Card and won an Ultra Ball from the lottery
Once I was finished with Goldenrod for the moment, I headed north to train my Pokemon. I visited Route 35, 36, and the National Park, defeating every trainer I came across.
Then, I backtracked to some previous areas to collect Apricorns. Along the way, I KOed the wild Pokemon I encountered in order to gain experience. When I was done picking Apricorns, I returned to Azalea Town, where I picked up some Fast Balls from Kurt and gave him all of my Pink Apricorns in return.
Finally, I continued training against wild Pokemon north of Goldenrod. I kept going until my whole team reached level 20. I originally wanted to get to level 21, but that would've taken me too long. I think I'll be okay for the Gym next time.