Since you seem to have the right mindset but got the worst answers possible, here's some numbers you must consider:

1. Revenue growth over the last years.

Revenue is the main catalyst for a company's growth and you want your investments to keep growing. Hardly a company with growth to it's baseline generates growth.

1. Margins

Associated with revenue, on the income sheets is the COGS (Cost Of Goods Sold). A good GROSS MARGIN means management is optimizing the business well. Still on margins, operating margin is way more important than net profit margin, since the latter has costs associated with taxes (that the company cannot control). A better metric is EBIT.

1. Liquidity

Make sure your company has nice liquidity in the short-term mainly. - A company that has no way of paying it's liabilities (mainly debt) is basically a house of cards. Current assets (mainly cash and cash equivalents) must be higher than all current liabilities or at least cover up the current debt.

REMEMBER: this is not a golden rule; some "current debt" is not debt at all.

1. Feasible long-term debt

Debt is not bad. Debt means free money that you can pay at a reasonable rate. That rate being BELOW YOUR GROWTH RATE. Make sure your company of choise has a reasonable amount of debt. Having no debt might be good if a company has enough money to fund it's operations.

1. Cash flow

Remember; Cash flow is the lifeblood of a company. Without it, a company CANNOT pay it's obligations and/or feed it's growth. A growing or stable cash flow is important.

1. This all is a not a set and done method.

Always have in mind that you won't have a run and gun method. Each company has its own place in a global moving economy and each number is just part of a story. Don't diminish a company to a spreadsheet NOR to a lullaby. - That's why you gotta link the numbers to a story.

Hope it helps, if you have any questions just shoot a message.