There's so many 'Top Tips', but my toppiest (yes, it is a real word!) tip would be;
All Codeclubs are unique.
What I mean by this, is that every club works differently, and what works well in one club may not work for your club. It's very easy, especially if you're on social media, to see all the amazing things that other clubs are doing and think that you have to do the same.
If you have the skills, time, and the right mix of kids, then go for it! after all, it might just work and the kids will love it. But don't worry if you don't have the right kit to do Physical Computing, or you don't have the knowledge or confidence to do HTML. Keeping within your comfort zone, especially if you're a new club, is absolutely fine. The Scratch Module 1 projects are ideal for new clubbers (whether kids or teachers/volunteers) and will be guaranteed to introduce the kids to new programming concepts in almost all settings.
Conversely, don't think that you have to use a formal 'teachery' (yes, that's a real word too) approach to your sessions. If you're used to that sort of environment or, for your own sanity, want to keep things nice and orderly, then that's fine. Personally, I find that quite dull (for both the kids and myself) and I use a more 'unstructured' approach, especially when the club has 20+ kids from across the whole of KS2 (7-11), where they start of with the standard Codeclub resources, taken at their own pace. When they've worked through (or got tired of) the Scratch projects, they can choose where to go next. Some progress to Python or HTML, some have a go with the Microbits or Raspberry Pi's, and others will go completely freestyle with their own projects.
IMHO, the learning aspect of Codeclub is not the main objective. The main thing is that the kids are having fun and becoming more confident in using computers as a creative tool. And don't forget, you need to have fun too!
If you do want to do something different; maybe some Physical Computing, or programming robots, but your club doesn't have the kit; get in touch with your Regional Coordinator who may be able to put you in touch with someone that can lend you some kit (and some expertise) for a session or two), or reach out on Twitter, on the forum, or at a Codeclub Meetup.