1. Edit your server.cfg file and change the Max Build Area from 10 to 50 (more is fine, but 50 is enough and not so much that the brush size bar becomes difficult, and all you need for beginner building until you're ready to start doing much bigger capital ships).
2. For black hulls, sometimes using the advanced build mode Display tab you can lighten your building area, which helps a tiny bit, and also you can turn your ship to catch light from a star at an angle which shows the block lines better, which can also help.
3. Since your core is how you access the ship, and it's the first element and can't be moved, the first thing many people build is the cockpit or bridge around the core.
4. While it is totally possible to build a hull that looks the way you want it to, and then fill it in with systems... you may still want to experiment with building systems-first so you can get a better idea of how they relate and can be organized effectively before trying to puzzle out how to squeeze an effective ship systems complex into a good looking hull you've pre-chosen, which can be challenging. Build your bridge/cockpit, then lay out a reactor, chambers, shields, thrusters, and finally weapons (I like this order, but still often vary it), then if you want you can figure out a way to wrap a hull around it and make it look good as a unique creation or just treat it as a naked test platform to experiment with ship systems.
5. Saved copy-paste templates are extremely useful for common elements like chairs and decorative consoles you use on many ships, as well as hallways, whole rooms, basic hull segments, and even system elements like a reactor+chambers layout you develop that turns out to be very versatile for your build style. It lets you customize a personal set of tools to speed building.
6. Make sure you experiment with different aspects of symmetry, templates, brush sizes and the build helpers before launching into any remotely serious build project on even a small ship.
7. Don't be too afraid of the system integrity numbers or let them totally dominate your build decisions. Any integrity over 100 is more than fine for most system shapes because, except in a few circumstances, damage is as likely to raise the system integrity or not affect it at all as it is to tank it. Exceptions might be your reactor and chambers, because you want exceptional integrity for the most vital part of your ship.
8. Chamber health contributes to total reactor HP, so by placing chambers short distance away from your reactor core you take some of your eggs out of the single basket, but you expose them to the risk of having their conduits severed. It's a trade-off that will be different for each ship type and player style, but you can also run multiple conduits for each chamber to create backup channels and a bit of redundancy for a more resilient ship.
9. One ship can't simultaneously be amazing at combat, salvage, and fast travel which means you always need a strategy for your ship build. It helps to build a few complimentary versions of successful ship models when possible. When I am happy with an escort, I will typically outfit a long-range (FTL buffs, maybe stealth) and short range (defenses, impulse speed, maybe scan buffs) version of it, one for strong defense near base, the other for hunting abroad. Same for miners. It's so easy to swap out a few bits. Easier than building a ship from scratch for each role. This is also a reason to do your best to keep essential system layouts clean, clear, organized and easy to see as much as possible within your creative vision in order to make versioning and even modifications on-the-fly intuitive and easy.
10. I recommend starting with a few small, fun projects before launching into a real ship.
11. Save copies of your ship regularly, but also save versioned copies at different stages of completion so you can back up to an earlier point easily if you decide you've gone astray.
12. Since you can admin spawn infinite free copies of saved ships, once you've saved a final draft of your ship, start spawning in copies of it to destroy in various ways and see how it behaves. Spawn in pirates to test it against. Spawn in a pirate version of the ship itself for a mirror match. Get an idea of how it handles in combat then consider making adjustments (of course nothing is invincible, so at a certain point you have to accept that it is as good as you can get a ship of that size and style).
13. Visit the Community Content section here frequently, and start downloading interesting ships. You can spawn them into your solo server for dissection and reverse engineering. This is a very important way to learn about how others build, just make sure the ships you download are built in Power 2.0. When you make a nice ship or project, upload it and share - don't worry about whether it's amazing or gets high ratings; it's as much about collective learning and sharing as it as about competing to build the coolest ship. Many of the best reviewers will give your creations some harsh criticism, but most will also make important suggestions about ways you might improve what you have, and content uploads can be updated with new versions as you improve them.