People faming you, or wearing an equip that'll give you charm. Cash Shop items give charm and certain equips like some weapons give you charm. You could also use "perfume" which is a monster drop most commonly found in Monster Park.
LMAO getting charm is not the end to get the pocket slot
get to lv30 charm (fame, NX equips, hair change, color change, do PQ)
once u reached lv30 in charm, a quest will come to u automatically (either light bulb on head, or check ur left hand side on screen)
Accept quest, head to hair salon in henesy, talk to the bigheadward guy (i forgot his name), he'll ask u to bring him one "Rose clipping"
Rose clipping can be obtained if u're a herbalist, so dig ur way home hehe
or u can buy from fm, about 25-30m each.
Some good pocket slot items: monster park pocket slot gives 2atk and some stats; PVP pocket slot item gives 3atk or 5atk (higher atk means more gallants emblem needed); or u can juz buy those crappy pocket item from npc in henesy ^^
Hope this helps, good luck bro