Tips and pointers

Today I attempted my first smuggling delivery, on a ground mission, and promptly got into a firefight with security which ended in a trip to a medical ship.

I was supposed to deliver a package to a specific contact at a surface settlement, couldn't find him on the grounds, and tried to enter the Hab building using an e-breach, to look for my contact there. Being relatively new to on-foot gameplay at settlements, I didn't realize doing that would alert the guards (again, newbie) that were near that door.

So, what is the trick to smuggling missions like this?

Also, I had a mission where I had to collect an item from a locked box. It was supposed to be in the habitat building, but to get to the inner room, beyond the airlock area, I had to cross a restricted area line. This of course alerted the guards as well.

So, in both of these scenarios, what is the best and easiest way to approach things? What can I do differently? Also, any tips and pointers for ground combat would be great. I'm coming from third-person shooters, but want to master the FPS gameplay. A lot of my shots miss the target. Do I just need to get into ground combat zones, and practice? I'm also using grade 1 suits and weapons. Shoud I focus on upgrading my gear before doing any more ground missions? All the missions have been threat 0 level, I think. Sorry for the long post.

Thanks, CMDRs!