It is ideal to practice in loose comfy clothing that you could move freely in.  Have a sweater or blanket nearby as you might cool down during the final relaxation.

Things you might need for your practice: a yoga mat to prevent you from slipping on the ground and to provide some cushioning if you are on a hard surface.  The cheapest ones tend to fall apart quickly, and the expensive ones are not necessary.  If you can’t make it t the ground, then a sturdy chair can be a good friend.  It is also good to have either a cushion or a block to sit on, if it is uncomfortable to sit for extended periods with your legs crossed.  The last item you need, often the hardest to find, is an open mind.