What is the best flea and tick product for dogs?

I have a lhasa apso who was recently adopted. She keeps scratching herself so I believe she has fleas. She was recently spayed so she cant bathe for ten days. I use to use the flea collar on my other dog but it didn't work. I heard front line was a great product and i want something that will work well for her. what products have you used and thought were great. Any information would be helpful !