The group that I play in has 9 characters, and 2 of us have exactly one level of cleric. Myself, I am a Ari1/Clr1/Pal4 and I worship the Goddess of Law, Knowledge and Fair Trade, and I refuse to heal people who do not selflessley aid others or pursue good goals, so my healing is limited. The other cleric is a Ftr5/Clr1 and he worships the god of War, so healing isn't his focus either. We have no Bards or Druids, and our ranger is multiclassed and can't cast spells. Basically it has taught us to plan and prepare better, to minimize getting hurt. It has also taught us to retreat if necessary. We also rely on missle weapons more in order to do as much damage as we can before engaging in melee. All in all, you just have to prepare and plan better to avoid any unecessary damage from being inflicted on you. It also means that you may have to spend your money on healing potions and to learn when the best time to use them may be. It has made us better players and group unity and the spirit of cooperation is much higher now that we don't have a real healer.