You should consider a shareholders' agreement as a "pre-nuptial" agreement. You are trying to reach a consensus in advance of a possible breakdown in the relationship. 1 in 3 marriages fail and the failure rate for business is much higher. Negotiating with your business partners ought to be a lot easier than with your spouse as the "don't you love me" doesn't come into it!

Here is a non-exhaustive list which you could use as a limited agenda for discussions between proposed or existing shareholders. This should be followed by detailed legal advice and then a written agreement between the parties.

1. Alternatives: limited company, partnership or limited liability partnership etc

Assuming you select a limited company:

2. Purpose of venture. Business plan. Expectations.

3. Share split

a. Implications of key thresholds: 5%, 10%, >25%, 50%, >50%, 75%
b. Deadlock vs controlling stake vs negative control/ability to block
c. "Ordinary", "Special", "Written" resolutions
d. class: ordinary, preferred, redeemable etc
e. dilution (now and future)

4. Directors

a. Day-to-day management
b. How many
c. Right to appoint/remove
d. Chairman; casting vote?
e. Service agreements: salary level?

5. Company name, company secretary, registered office, accountant/auditor

6. Finance

a. Share capital vs debt
i. Allotment of new shares
ii. Cash/non-cash
iii. Director's loan
iv. Second round
b. Security? Debentures/charges. Personal guarantees. Indemnity to each other?
c. Working capital
d. Bank mandate: joint signatories?
e. Dividend policy
i. consider minimum % profits to be distributed or retained if no agreement
ii. dividend versus salary balance

7. Business plan and budget incl cash flow; agreed intervals

8. Exit strategy (the important one!)

a. Share valuation mechanism
b. Discount/premium for certain stakes
c. Ability to transfer part or whole stake only
d. Staggered exit – tax and valuation implications
e. Trigger events eg
i. Death/serious illness
ii. Divorce
iii. Trade sale
iv. One party wishes to leave
f. When to wind company up
g. Pre-emption rights
h. Ability to transfer to spouse/children
i. "Shoot-out" provision: party receiving notice must elect either to purchase shares of other party or sell its shares to that party
j. "Bring-along" provision: transferor must require third party purchaser to offer to buy also the other party's interest at the same price per share
k. "Drag-along" provision: selling party can oblige other party also to transfer its shares to the same purchaser
l. Put/call options included at outset

9. Matters requiring unanimity

10. Dispute/deadlock resolution mechanism (Ultimate sanction: specific right after minimum period for either party to call for liquidation)

11. Personal tax planning issues affecting structure

12. Intellectual property

13. Non-compete/non-solicitation

14. Confidentiality

15. Life/term assurance: key man, cross option