Congratulations on getting it finished, hope your happy with your time.
Focusing on the shorter distances will improve you massively, example: 5k for 10k, 10k for 21.1k and 21.1k for the 42.2k. With a solid 5k time, leg pace at the slower paces as distances get further will become really easy.
The best thing to improve is a coach or follow a program. I use to train on my own and got my half down to 1:24:5-something. Then I joined a local club and started training under a coach and 8 months of solid work got down to 1:14:19 and now am training to hopefully crack 1:10.







