guille, hi, im from argentina too, and as you im trying to increase my flying skills in pattern,

what RCpattern said was excelent, always practise one manouver per day, it didnt result for me practising 2 or 3 manouvers in one day, just pick one, and repeat it again and again for 2 or three weeks ,and the results will be excelent, if you have someone near you to help seeing the geometry, better
yes sometimes some sessions can be frustrating , but dont be desapointed, results came with practice and time, ( im still waiting for them!!!! )

also before going to the field, i "fly" the airplane at home, memorize every step, and see the flight in your mind, make it sistematic, and you wont improvise at the flying field

straight and level, THE MOST IMPORTANT

good luck, despite im not an expert, i hope this can help you