I nap every single day for around 2 hours...best thing to do that i found is to deprive yourself of your usual amount of sleep...so for example if you normally sleep for 8 hours, cut it down to 6. This way when you finally have time to nap your body will be more tired than usual. Once you get used to this pattern your body will most likely expect to fall asleep at the usual napping time, meaning that you arent as tired when you first wake up but when you get close to your nap time you start to feel tired once again.

For a good example i will share with you my nap patterns: I go to bed at 10PM every night and i wake up at 5:10 AM (i have work SUPER early), I then work for 4 hours, come home and sleep for another 2. I start off pretty alert but as it draws nearer to 10AM i start to feel tired..which allows me to easily go to sleep when i nap!