The best thing I can think of as far as general advice is probably to try and find a local build group. This will help you connect with people in your area who are also into the hobby, share builds, tips, local sales, meet up for build days, etc.
Don't throw anything from the kit away until it's completely done and on the shelf. I've learned the hard way that sometimes pieces can get knocked off the runners and into the bags.
If you end up breaking a piece, try fixing it yourself before trying to get a replacement. Doing so will save time and you can learn a new skill, or at least gain experience. On that note, plastic cement (I use Tamiya extra thin) works better than any kind of glue for polystyrene (the plastic most Gunpla parts are made from).
Don't be afraid to look outside Gunpla communities for advice and tips. Scale modeling has been around for much longer than Gunpla, and those folks have decades of experience and shared knowledge to draw from, most of which can be applied to Gunpla.