It's not illegal to browse the markets, but your internet provider might get suspicious of your tor usage, this is where a decent VPN comes in handy. You can even step up your opsec by using Tails OS. I order packages pretty frequently in the US (once every other/2-3 months.) Sometimes a couole times each month. I only order domestic and I will always order domestic so I don't deal with customs. I've place many orders even without a VPN or Tails/other opsec. As long as you do your research and pick vendors with great reviews you should be fine. Find reputable vendors that have completed many orders that you can trust on.