1. get a 2:1 from a good uni
2. be quantitatively literate
3. have good social skills and be able to project confidence
4. get experience*
5. look the part**
6. god help you if your CV or covering letter includes typos/grammatical howlers
7. network, but without being a pushy try-hard
8. be open minded about what you try - insurance, shipbroking etc - and do not limit yourself to 'graduate' roles
9. be lucky
*relevant experience is great but any actual work experience where you show up on time, do a good job and show initiative will help. even retail or whatever where you deal with members of the public can be great at building skills and confidence dealing with people. I used to supervise trainee solicitors and there were two reliable predictors of whether they would be good with clients - public school or customer facing work experience, both of which build confidence dealing with people
**this depends on the job up to a point but if you are talking professional services you want to dress conservatively, especially for interviews. rightly or wrongly plenty of people (but not all) will judge you for a silly haircut, visible tattoos, whatever... express your 'individuality' once you have a foot in the door