Earning season has officially started, and I must say that I’m looking forward to what the next few weeks will bring. Now, as I’ve mentioned earlier, we are entering a “peak earnings” environment and it’s getting more and more difficult for companies to accelerate sales and earnings compared with Q1 2011.

This also means it’s going to be even easier to separate the “wheat from the chaff”—essentially, strong companies will continue to accelerate earnings as underperforming companies get left behind. The best move for investors is to focus on only those stocks that are able to beat estimates in this environment—if a company is able to accelerate earnings in this tough environment, that should be a green light for the stock

So let’s take a moment to review some of the biggest earnings winners from the past two days, starting with Alcoa (NYSE:AA), which traditionally begins earnings season:

Alcoa kicked off earnings season on the right foot by posting better than expected bottom-line performance for the first quarter.

Compared with the same quarter last year, net income did dip from $308 million, or 27 cents per share, to $94 million, or 9 cents per share. However, excluding the impact of special one-time items, adjusted net income weighed in at $105 million, or 10 cents per share. Meanwhile, analysts expected Alcoa to post a loss of  (4) cents per share, so the company trounced estimates. Over the same period, sales climbed 1% to $6.01 billion; this also topped the $5.77 billion consensus sales estimate by 4%.

Looking ahead to the rest of the year, management expects 7% growth in global aluminum demand, compared with 10% growth in 2011. Investors were excited with this earnings announcement, sending shares of AA up.

We also had a good turnout from several other stocks, including:

Standard Microsystems (NASDAQ:SMSC), a chipmaker that trounced the (17) cents earnings per share estimate by posting a profit of 5 cents per share for the fourth quarter. Shares zoomed ahead on Wednesday.

Mattress Firm Holding (NASDAQ:MFRM), which trumped the 20 cents per share consensus estimate by 180%; the company posted profits of 56 cents per share for the quarter. Shares of MFRM spiked 18%.

Titan Machinery (NASDAQ:TITN) topped the 84 cents per share  consensus earnings estimate by 62%, bringing in profits of 84 cents per share for the fourth quarter. Investors reacted favorably to this announcement, causing shares of TITN to skyrocket.

And I’m sure that the best is yet to come. Later on this week, we have a few high-profile earnings announcements, including:

• Google (NASDAQ:GOOG), which is scheduled to report earnings after close on Thursday. Analysts call for 24.6% sales growth and 19% earnings growth.

• Rite Aid (NYSE:RAD), which is announcing earnings before market open on Thursday. The Street expects Rite Aid to grow sales by 8.9% and earnings by 41.7%.

• JPMorgan Chase (NYSE:JPM), which is releasing earnings before the opening bell on Friday. JPMorgan is headed towards a 4.4% year-over-year sales loss and an 8.6% profit loss.

• Wells Fargo (NYSE:WFC), which is announcing earnings at 8:00 a.m. E.T. on Friday. The bank is expected to grow sales by 0.5% and earnings by 9%.

I’ll keep tabs on these earnings announcements as they come out in upcoming posts, and in the meantime, happy earnings season!