It's been said that "the best stock might be one that you already own."

With that philosophy firmly in mind, I've decided to add to two of my current positions in my Special Situations portfolio. Each offers compelling potential for return over the next few years.

Tile Shop Holdings (NASDAQ: TTS)
Of these two, Tile Shop has the best potential for long-term gains. Thinking 10 years out, it's hard not to see this as a three- or four-bagger, if the company continues to execute as it has. The company recently increased its store count growth expectations for the year, and same-store sales have been on fire. Sure, that makes it tougher for next year's comps to be as impressive, but Tile Shop is riding the wave of an improving home market and the new fashion for tile. So for me, it's a stock to "buy on the dips." And yes, it is pricey, but the best stocks often are.

Because it's a high-growth stock, it's prone to extreme pullbacks in the event of a market meltdown, but that would just give me an opportunity to buy more Tile Shop. I'm already up 50% in less than a year, and I'll be adding $1,000 to this stock.

First Financial Northwest (NASDAQ: FFNW)
The situation at First Financial has improved in recent weeks. After announcing a 10% stock-buyback authorization in May, the company wasted no time in completing it. Then it went one better, by announcing a 5% buyback authorization. That's exactly what I want to see from profitable banks trading below tangible book value. I wouldn't be too surprised to see yet another buyback announced.

Activist Joseph Stilwell is doing what it takes to clean up this bank and improve returns for shareholders. When he ran for a directorship last year, Stilwell promised that he would look to sell the company. That course looks even more sure now that Victor Karpiak has been ousted from his role as CEO. I think this stock has low downside, and it's riding the strong Seattle economy. My position is up 33% in less than a year, and I'm adding $2,000.

Interested in any of these stocks or have another stock to share? Join me on my discussion board and follow me on Twitter (@TMFRoyal).

Jim Royal owns shares of First Financial Northwest. The Motley Fool recommends Tile Shop Holdings and owns shares of First Financial Northwest and Tile Shop Holdings. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.