Spaniard Nadal, 27, won on the hard courts in Doha at the start of the season before a back injury wrecked his chances in the Australian Open final at the end of January.
He returned to take the title on clay in Rio de Janeiro the following month and reached the final of last week's Sony Open hard-court event, where he was beaten 6-3 6-3 by second-ranked Novak Djokovic of Serbia.
He will be bidding for a ninth title at the Monte Carlo Masters later this month before more clay events at Barcelona, Madrid and Rome and then the French Open starting at the end of May, where he is also chasing a ninth trophy.
Nadal said he was "more pleased than sad" about his performance on the Miami hard courts but admitted that Djokovic had been much the superior performer.
"In the Miami final I was not at the level of Djokovic, obviously he was quite a bit better than me," Nadal said at an event organised by new sponsor Banc Sabadell.
"But it was important for me in terms of confidence for the clay season," he added.
"As always I am coming into the clay swing with the maximum level of hopeful anticipation and I am eager to do well and eager to start training on clay.
"I think I have started the season quite well, not fantastic but good.
"I have a favourable history on clay but history doesn't help you much in the present.
"The only thing I can do is try to work hard and get to the clay season well prepared in tennis terms and in good physical and mental shape."
Forty-three of Nadal's 62 singles titles have come on clay, including eight at the Barcelona Open, two in Madrid on red dirt and seven in Rome. He has 13 grand slam singles titles and a record 26 Masters crowns.
- Sports & Recreation
- Novak Djokovic