A survey of 650 NQTs found more than half worried about paperwork, class sizes, the pay and status of teachers, and budgets and resources at their school.
But four out of five said their course had increased their enthusiasm and most said it had developed their confidence and competence.
The survey, for supply agency TimePlan Education Group, pointed out the recruitment crisis in London - 21 per cent ruled out working there and another 4 per cent ruled out all cities.
Two-thirds had found jobs by August. But 11 per cent had already decided to drop out and 12 per cent said the course had reduced their desire to teach - some citing a lack of support during teaching practice.
Others attributed a loss of enthusiasm to moaning teachers complaining about low pay, heavy workloads and high stress.
Nearly all cited location and team spirit as reasons for choosing a school; its size (79 per cent), reputation or OFSTED report (82 per cent) and budget (67 per cent) were also important.
Also key were pupils' perceived behaviour (71 per cent), socio-economic status (43 per cent) and whether the school was "demanding" (64 per cent).
Nine out of 10 were attracted to teaching as "rewarding", while half were passionate about their subject. Job security attracted a third, but pay attracted only one in five. Only 1 per cent were persuaded by media advertising.