Early in the game, it's hardly likely someone would invade you. One reason being that only someone with similar stats as you can invade (and since they just started too, might just be playing the game as opposed to invading people most likely). The other reason is that no one can invade you in soul form. You get to soul form when you die (which you will) and the only way to get back to human form is to either kill a boss, invade someone or use a somewhat rare item. So it's more likely you'll be playing most of the game in soul form ;) Also, you cannot be invaded in an area in which you defeated the boss.
Lastly, you won't be able to see bloodstains and messages if you play offline, so that'll be up to you. Then there's world tendency...but i'll leave all that up to you.
