The American left-hander, who has made a career habit of winning in the first four months of the US season, triumphed by four shots after closing with a four-under-par 67 at the TPC Scottsdale.
"It's important to start building momentum," Mickelson said about the April 11-14 Masters at Augusta National in Georgia after finishing just two strokes shy of the US Tour low for 72 holes.
"But it's more important what you do closer to Augusta, that you start feeling confident in your game then, that you start getting good touch on quick greens.
"Certainly having been in contention and being able to come out on top is an important element going into the Masters if you want to do well because you've got to deal with some of the greatest pressure you will ever feel at the Masters."
It was the 28th time Mickelson had triumphed on the US Tour before the end of April, while the title was his 41st overall on the circuit.
He has now won at least once in 20 different seasons on American soil, with only Sam Snead (24 seasons) and Jack Nicklaus (21) ahead of him.
"I feel like my game is on the up-swing," the four-times major champion said after finishing at 28-under 256, just two short of the US Tour record of 254 posted by Tommy Armour III at the 2003 Valero Texas Open.
"I felt like it was on the up-swing towards the latter part of last year, at the Ryder Cup, then I went over to China and played well and I had a great off-season."
Mickelson, who will be defending his Pebble Beach National Pro-Am title next week in his native California, had been taken aback after tying for 37th and 51st in his first two US Tour starts this year.
"The first two weeks I felt were an anomaly," the 42-year-old said. "I was putting so well heading into the year, to play the way I played those first two weeks was surprising to me.
"This is how I've been playing for a while and it feels really good to get that golf out of me when it matters," he said of his form at the TPC Scottsdale, where he took control of the tournament with a sizzling 11-under 60 in the opening round.
"Today, relative to the first three days, my game was fractionally off. But I hit a lot of good shots today, I just did what I had to do to win, that's all I cared about."
Mickelson, often wayward off the tee during a career marked by brilliant shot-making and a few stunning collapses, was especially excited by his driving accuracy this week.
"I had something really important happen to me on Tuesday when I got this (new) driver," he said. "This has really changed my game. I drove it phenomenal all week.
"It feels so easy to hit, and the (fairway) misses are so much better. I really think this is going to help my career and my year."
Overall, Mickelson was hugely relieved to win for the first time on the US Tour in almost a year.
"When you haven't won in a while, you want it bad," he said after holding off a last-day charge by Brandt Snedeker, who closed with seven-birdie 65. "I was nervous heading into today's round. It means a lot to get back into the winner's circle."
As for his build-up to the 2013 Masters, Mickelson was delighted to experience the thrill of winning again just two months out.
"Having opportunities like here to play in contention over the weekend and lead wire-to-wire, that type of pressure and learning to deal with it gives me confidence and some confidence heading in (to Augusta)," he smiled.