Grass is much nicer and friendlier than tarmac. It's what aeroplanes were made to fly from.
Watch out for bumps, keep the stick further back than you do on tarmac and obviously if it's a tailwheel aircraft keep it right back all the time. Also, be careful of sliding on wet grass when braking (need to brake less on grass anyway) and be very careful of taking off from long wet grass with a load on.
Otherwise, enjoy.
QDM