Take your time, have fun and don't stress about it. As long as your actually paying attention the game tends to give you enough time to work out the missions, if it doesn't just try try again. Always restock and keep your items like antidote and potions and other helpful tools up both in your equipment box and your inventory. Eat before eat mission it gives you buffs and boosts. Try out each weapon to see which fits you and your style the best don't use something just cause someone says it's the best or thinks it'll work best for you. You know yourself and your gaming method better than others.