Achieving the financial freedom to retire early a dream for most. Making that dream a reality isn't as tricky as it sounds. The secret is simple: Save a lot more each month. Sounds easy, right? Not so fast.Usually, advisors advise 15% to 20% of total income saved every month as an objective - yet in the event that you want to retire earlier, you likely need to tighten that number up to 40% or half of your pay. Not a discipline easily practiced when you review or consider that a substantial segment of your paycheck goes to basic, non- negotiable lifestyle needs. But if you are willing to make some serious lifestyle adjustments and trade-offs, it's achievable.A generally new development called Financial Independence, Retire Early (FIRE) has been created around this "sacrifice and over-save now to retire early" idea. FIRE supporters create exacting savings plans (up to 75% of income) and make related compromises like living in small homes, walking to work every day, prohibitive weight control plans, etc. This way might be unreasonably prohibitive for many, yet the mentality offers a few takeaways that may merit consideration.To start, stick with the essentials of long-term growth investing: Build a diversified portfolio of stocks with exposure to various styles, sizes, sectors, and regions.To accelerate the retirement investment cycle, you can construct a portfolio designed with more risk - and the potential for higher returns - but it should still be appropriately diversified to protect against larger than average market drawdowns that can be difficult to recover from and ruin any chance to accomplish your early retirement goal. There are numerous ways to diversify a portfolio, and how you do so should depend on your age, your risk tolerance, your growth and income needs, and your long-term goals.Once you've begun saving at a higher rate and you have an investment plan, put that money to work in your plan as quickly as you can. Don't worry about finding the "perfect time" to invest - simply put the money in and keep it in. Let compounding work to help you grow your retirement savings at an exponential rate.Growth stocks with low beta, strong earnings estimates, positive sales growth, and expected future growth are an excellent way to determine investable growth stocks for your retirement.The Zacks Rank regularly identifies attractive growth stocks ideal for retirement investing. Here are just a few that might be worth consideration: Virtu Financial (VIRT), Vistra Energy Corp. (VST) and Waterstone Financial (WSBF). These are top-ranked stocks, with at least 5% earnings and sales growth over the past five years, and boast beta equal to or lower than 1.Do You Know the Top 9 Retirement Investing Mistakes?Whether you're planning to retire early or not, don't let investing mistakes derail your plans.If you have $500,000 or more to invest and want to learn more, click the link to download our free report, 9 Retirement Mistakes that will Ruin Your Retirement.This report will help you steer clear of the most common mistakes, like trying to time the market, lack of diversification in your portfolio, and many more. Get Your FREE Guide Now Waterstone Financial, Inc. (WSBF): Free Stock Analysis Report Virtu Financial, Inc. (VIRT): Free Stock Analysis Report Vistra Energy Corp. (VST): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research