Cool. What's the best way to minimize transactional costs when buying ETFs (as a buy-and-hold strategy)? E.g. Should I only purchase marketable round lots? Can I do any better than Fidelity/Interactive Brokers for price improvement? Any tips to make my trades as efficient as possible? Or would you avoid ETFs altogether and just purchase mutual funds directly from Vanguard, without any transactional costs? Thanks!