How to gain money
Now you are past the first job you should have no problem getting money to afford pots. However, if you want decent weapons and equipments you better know how to gain money or else it will take you ages to get your dream weapon and equipment. Ways of gaining money I've already mentioned in my previous paragraphs are buy/sell, scrolling, quests, and getting drops. All the above 30 quests are mostly profeitable. Trading is a bit different from below level 30. Now you have enough money to invest on better items such as scrolled weapons/equipments, scrolls, ores, and quest items.
If you don't gain money, don't give up. My opinion, level 30-40 is the HARDEST and MOST BORING period of levels. You will depend on drops from evil eyes, boars, fire boars, jr kitties, and curse eyes (exluding the ludi monsters because I do not know their level of efficiency of training) and they drop barely any good equipments that will make you rich. From level 40 to 50, training might still get dull, but the drops aren't as bad. Now, from level 50 to 60 you will notice that you will gain a HUGE amount of money from drops. From level 30-40 I barely made a million, level 40-50 around 3 million, level 50-60 30 million. My point is if you think you are not getting rich from level 30-50, bare the hardships, because after that period you will find your wallet overflooded with  maple stroy mesos.

Leveling areas that will make you rich
From level 30-40 level at brown teddy, drum bunny, fire boars, jr kitties, dark letties, lorangs, latz, pink teddy, Roloduck, Tick, Panda Teddy, Chronos
From level 40-50 level at fire boars, copper drakes, jr pepes, lunar pixies, chronos, zombie lupins, tick tock, Platoon Chronos, Tobo
From level 50-60 level at drakes, clang, umti, wraiths, jr yeti, kitties, hectors, lunar pixies, Platoon Chronos, Master Chronos, Tobo, Master Robo
From level 60-70 level at cargos, tauromacis, dark stone gollems, yetis, white pangs, Soul Teddy, Master Soul Teddy, Buffy, Lazy Buffy
From level 70+ level at...anywhere you want (except for bains, thantos, gatekeeper, Papulatus until 80/90 ish)

Hunting for High Levels (lvl 30 or above)

How to hunt efficiently
Hunt monsters that you can kill within 5 hits that usually have low kb or speed from level 30-60. 70+ you can hunt any monsters you want as long as you don't get killed within 3 hits. Party would be REALLy helpful for hunts. Always have a cleric or an assasin in your party, or both in a big hunt.

Places to hunt
Some places to hunt for level 60 or below are yetis, dark yetis, cargos, tauromacis, taurospears, werewovles, Soul Teddy, Master Soul Teddy, Buffy, Lazy Buffy, Klock, Lucidias, Cerebes
Places to hunt for level 60+ are tauromacis, yetis, dark yetis, Lucidias, Cerebes, ynp, dark ynp, werewolves, lycanthropes, jr rog, c rog, Buffoon, dark klock, deep buffroon, bains, Ghost Pirate, death teddy, master death teddy, dual ghost pirate, Spirit Viking, Phantom Watch, Grim Phantom Watch, Gigantic Spirit Viking, Thantos, Gatekeeper

Pros/Cons
Pros: way better drops than regular training, fun, more  maple stroy mesos  per monster
Cons: wastes time, spends more money on pots than regular training, chance of dying