For Tom Blomfield, co-founder of Mondo, people often miss one of the most important factor when they choose to work in a startup: its size and stage. To him, it's sometimes even more important than the industry or the idea itself.

BOOTSTRAPPING Two to four people are working long hours in a bedroom to get a working prototype. There’s no funding and no salary. The product vision is vague and broad, and the team is focused on learning and iterating quickly. Everyone does whatever needs to be done.

SEED-FUNDED The company has a working prototype, a few dozen regular users and £250k of seed funding. You are granted with 3% equity plus whatever basic salary you need to survive. Even if you’re not making the decisions, you hear about them immediately. At this stage, there’s still a good chance that the company fails to find product-market fit.

SERIES A The company has thousands of paying customers, appears in the “ones to watch” articles in tech press, raised £3m from a big-name VC and the team has grown to 10-15 people. You get 0.5% in stock options with a salary that’s 10-30% below market rate. You’ve got your own office, or at least your own area in the coworking space. The company sets out a quarterly product roadmap, and you’re asked what you think should be prioritized.

SERIES B The company is now 2-3 years old, has millions of paying customers in several countries, is regularly featured in the press, and has just raised £10-20m, increasing headcount to 60 people. The founders you met during your interview don’t always remember your name now you work here. Your salary is in line with the market, and you get 0.05% stock options. You have a couple of days’ training, but you still mostly figure it out along the way. At this stage, most people are focussed on “repeatable processes” and scaling up.

SERIES C After 5 years, the company has raised £100m at a £1bn valuation. When you join, you’re granted £50,000 of options, or 0.005% of the company. You are one of these 6 new Sales Associates focussing on a specific vertical in Dublin. The new office feels empty at first, but you’re surprised how quickly it fills up with new staff. You see the CEO on the cover of Forbes, but you’ve never actually met him, and you see consultants in the meeting rooms, but you don’t know what they’re doing. When the company get acquired, HR follows up explaining that some departments will be downsized. You’re told that your stock options are “underwater”; when you Google this, you find out that they’re worthless. You wonder why you ever joined a startup in the first place.

Source: http://tomblomfield.com/post/136759441870/when-to-join-a-startup