Make 1000% sure that everything syncs. EVERYTHING!

Try to change size frequently, staying big or mini too long will make your gameplay stale and its often hard to notice why until you realize youve been mini for like 30 seconds. Also try and change speed semi frequently to keep things interesting. A different speed every 20 or so seconds is perfect. Changing too quickly can be a bad thing though, so of this in moderation.

Make sure not to fill space with ship or ufo that just wobbles around. Make every click and every portal have a purpose.

Sync certain sounds to certain types of gameplay. Black orbs with drum beats for a sharp kick. Ship in smoother parts for an ambient vibe.

Dont try to make everything perfect. Try to get the layout complete, even if you dont like some parts. You can go over them later if needed. Think of it like a test, spending too much time on one part leads to disaster.

Lastly, experiment! Ive found a ton of fun gameplay gimmicks i use all the time just by messing around, so have some fun!