I've built this kit mostly OOB early this year, and though I enjoyed the build, my best advice is as follows:
- change the tracks. AFV Club has some nice ones and not that expensive. I used kit tracks and are really the worst part of the build (flash, sink holes and 2 links too long to fit right). Bronco are quite hard to build, many more parts than AFV Club.
- change the barrel, the kit one it's on the skinny side, I used a leftover plastic one from Meng Leo 1A3 build, and the difference its quite noticeble. I have some barrels from Leopard Workshop, seems to be easy to use, and look great. Cannot tell how they build, since they're still on its package.
- add mantlet covers, also from Leopard Workshop, a little hard to use but add a great look to the finished tank.
- change the MG3, the kit one it's awful, just do some kitbash, I actually used an old one from Italeri's Leopard 1 from the spare box.
- if you like, use some PE here and there, Revell parts are a bit oversized in places.
Here's a pic of how it turned out the build I mentioned, also added a figure from Dolp (not that well painted, but I'm improving...I think...) and the Hoffmann device from Tamiya, plus a few scratch things here and there. More pics are available here on Armorama Features.

I really like the look of the tank anyways, and I enjoyed it so much that I have another one to do, using some of the add ons recommended above.
Hope it helps, best regards