Level 22-24: Big Boars / Magma Thieves: Big Boars and Magma Thieves are nice, at LH3 there are Imps, and the Temple would also give nice exp.
Level 24-28: Cactus bees / Desert gosumis: Bees and Gosumis give good xp until lvl26-27 so you can also try dongs if you got a lot Newport 100'S Cigarettes Cheap Newport 100S Cigarettes of hit-rate. Ask for a party with a lurer (mage or warior) and 2 rangers but rangers can also lure bees cuz they're very slow. And if u are in a good guild you could get free lure 23-25: Desert Gosumi, Desert Sandmen / Siras should kill Desert Gosumi, or Desert Sandmen. The gosumi and sandmen drop Old Scrolls (which when u you double click it in the menu you get either recall scrolls or D, C, B, or an enchantment scroll) and other items such as thick leather that you can use to make armor and helmets. You should try to get a lure or a noob mage party so its easier to kill and the noob mage gets some nice little exp 26-29: This depends. If you are willing to risk dying (get Guardianship of Siras / Protection of Lanos from Secret Vendors to prevent losing that precious 1% when you die). If you have the money to get the Guardianship/Protection, then you could go and kill Redeye Gosumi / Sunset Flower (lower exp), desert sandmen / Doleys' (somewhat better), desert beholder / sand donguris, (They all drop the same items, but beholders and dongs seems to drop more items), or 3eyelizard / Desert Ambush (being the hardest). SHAAACK is the desert valley and BSSSZSSS in the arid grassland, that you might need to look out for. They can attack you when you are inside the glitch so either avoid him or kill him. (They're level 40 so look out.)
Level 29-40: Depending on your hit rate, you can kill Desert Ambushes or choose to move on to the hot sand plains and kill Shadows, Wanderers, Sandeaters, (providing you have sufficient hr/hit rate)