Best advice is slow and be patience. Start slow and indirect ie inside thighs etc. Then start VERY slowly on her clit. She will tell you if she wants more, and aim at always keeping in the state of wanting just a little more. If you start so slow you think she's not interested, keep going, because she will be and if you stop now, she'll hate you and never give you anything in return. If you start too fast and she's not into, she'll think your a lapdog trying to drink from a bowl.
Slow, pointed tongue on clit, variation around her lips and controlled is the best approach.