1) How much do the founders need you? This will be helpful in negotiations. 2) How will your role in the company effect its success? 3) How important is salary to you?
All the above will give you an idea of how much equity you can get (or are worth). Use the answers to these questions to help you negotiate.
If salary is really important to you then expect less equity. If you really believe in the company and are willing to work to make it successful then maybe you should go towards more equity and take less salary. This will pay off (much more) in the long run.
I would recommend that you let them make you an offer first. This will give you a baseline on what their expectations are. They might say.. 60K/year and 20,000 options. You need to ask them about the options:
1) What percentage of the company is the employee options pool? This might be 10 or 20%. 2) How many shares are in the option pool, or...what percentage of the option pool is 20,000 options. This will help you determine what actual percentage of the company you may be entitled to. 3) What is the vesting schedule?
Remember one thing when negotiating: You need to ask or you will not receive :).
Good luck!
There is something of a red flag in how you've phrased your question. It's curious that you say that you will be joining the company, but then your post is all about the fact that you haven't yet negotiated the equity you will be receiving. This makes the most sense when you only are considering joining the company. If you already have an agreement to join, then this agreement most likely stipulates what equity you are owed, and on what schedule it will vest.
Part of the overall package that is required to convince you to work for this company should include a specific % of the company's equity. Surely your bargaining position would be stronger if you hadn't already agreed to work for the company when making an ask for equity.
As a yardstick I would aim for 1.5x the rate of whatever the last round of investment was. AKA if they got 5 million and your giving up 50k then look for 10% of whatever the investor got vested over 3 years. (Also, the further from your market rate the shorter your vesting schedule needs to be.)
PS: Don't forget the idea is paying you in stock needs to be more expensive than paying you in cash or they are going to want to pay you in as much worthless stock as possible.
Sounded like a good deal as I was naive and this is my first time joining a startup and having to deal with all these equity thingy. Turns out after converting all preferred shares to common stock, there's virtually nothing much left.
You're also the first technical member, which means that you'll be building the entire product. You are responsible for the execution, which means you are critical to the success of the company.
Start negotiating at 20%.