Stay clear of:
1. Deep sand
2. Loose gravel
3. Mud
Oh wait! That's what off roading is!
I would recommend (as others have said) good tires. I'd stay clear of 50/50 tires and anything with a strip in the center. It really depends on how often you plan to ride off road. But eventually you'll encounter all the above and you'll be glad you had the right tire. Remember, everything is a compromise. A good dirt tire will not last long on the pavement. A good road tire will not work well in the dirt. My thumper came with saharas. blah. I really like pirelli scorpion XC mid hard. Loaded (the bike) it will start to wobble with just a slight shift in weight (cause the knobbies) but their great in the dirt. I also like Michelin T63. A little longer life on the tarmack but good in the dirt.
When I started to get dirty I bought a pressure suit and MX boots. Good investments IMHO. BTW fully loaded with a T63 in back and worn scorpion in front I topped out at just under a buck on the tarmack.
You may rethink lowered pegs off road.
Take it easy till you get your dirt legs.