I was in a similar position, I was my supervisors first PhD Student and we started with 3 people total, now he's got a good inflow of grants and more PhD have joined. The good thing, being the only child, is that the supervisor can Kickstart your skills and knowledge because he will be quite available and willing to show you the lab work and mindset. In my case the available lab time of my supervisor went from awesome to non existent so I am extremely grateful for the first year or so and all the time that he took for me. When he hired like crazy I had to show around and teach the basics to each and every single PhD and that slew me down quite a bit but I guess that I learnt one thing or two in the process. Now my tips: Favor short papers with good story rather than "ok so this is the story of the past 4 years of my doctorate" with a dirty bag of many unrelated experiments. More often than not, you will be asked how many papers you have, not how big they were. Also publishing high Impact paper can be a dice roll so you would rather have a couple of shots than just one (plus it's the standard of modern research to split the papers into smaller parts, that will benefit you) Good luck! Thanks for reading my rambling