I aim for a level per day, I'm one of the slower guys in our guild tho =P (IM NEW TO MAPLE! I DON'T KNOW HOW TO GRIND YET :c)
So I just party quest (to get rewards like glasses, slime shoes, altair earrings etc) and with that comes a lot of money and some exp.
Now the money is the important part, you always say you're very poor in comparison to everyone else, well money=equipment, good equipment=more damage per hit=more kills per hour=more exp.
Also note, after you have got money going then you can splash out on hiring things like ring mules, and buying nx (using mesos) for those 2x xp cards.
Also have you got a good family? I have a decent one, it brings in at least 4k rep per day. Thats enough for at least 30 mins of 2x exp per day. But if you can get 5k per day, thats enough for 2x exp for party, you can sell this for money (sell within guild for like 8m) and you also get 2x exp for 30 mins too.
Make money off this!
Also have you thought bout condensing your costs? Potions -New Leaf city.
Have you got any priest friends who could train with you and use holy symbol? 1.5x xp.
The recent level ups have mostly been from that golden pig event, so don't take much notice of them in comparison to your own. Note the speed of walzys levels up, they come in bursts - he doesn't level once a day, he levels like 5 in a day, then holds of for a week. The week is used for prep time for funds which he uses to hire a ring mule, buy rep exp, holy symbol etc.
Just use whatever method works for you