First and foremost is the timeliness of the notice:
Colo. Rev. Stat. Ann. § 4-9-612 (West)
(a) Except as otherwise provided in subsection (b) of this section, whether a notification is sent within a reasonable time is a question of fact.
(b) In a transaction other than a consumer transaction, a notification of disposition sent after default and ten days or more before the earliest time of disposition set forth in the notification is sent within a reasonable time before the disposition.
Next is the contents of the notice:
Colo. Rev. Stat. Ann. § 4-9-614 (West)
(a) In a consumer-goods transaction, the following rules apply:
(1) A notification of disposition must provide the following information:
(A) The information specified in section 4-9-613(1);
(B) A description of any liability for a deficiency of the person to which the notification is sent;
(C) A telephone number and mailing address from which the amount that must be paid to the secured party to redeem the collateral under section 4-9-623 is available; and
(D) A telephone number and mailing address from which additional information concerning the disposition and the obligation secured is available.
(2) A particular phrasing of the notification is not required.
(3) The following form of notification, when completed, provides sufficient information:
[Name and address of secured party]
NOTICE OF OUR PLAN TO SELL PROPERTY
[Name and address of any obligor who is also a debtor]
Subject: [Identification of Transaction]
We have your [describe collateral], because you broke promises in our agreement.
[For a public disposition:]
We will sell [describe collateral] at public sale. A sale could include a lease or license. The sale will be held as follows:
You may attend the sale and bring bidders if you want.
[For a private disposition:]
We will sell [describe collateral] at private sale sometime after [date]. A sale could include a lease or license.
The money that we get from the sale (after paying our costs) will reduce the amount you owe. If we get less money than you owe, you [will or will not, as applicable] still owe us the difference. If we get more money than you owe, you will get the extra money, unless we must pay it to someone else.
You can get the property back at any time before we sell it by paying us the full amount you owe (not just the past due payments), including our expenses. To learn the exact amount you must pay, call us at [telephone number] or write us at [secured party's address].
If you want us to explain to you in writing how we have figured the amount that you owe us, you may call us at [telephone number] [or write us at [secured party's address] ] and request a written explanation. [We will charge you $ __________ for the explanation if we have already sent you an explanation of the type requested within the last six months.]
If you need more information about the sale call us at [telephone number] [or write us at [secured party's address] ].
We are sending this notice to the following other people who have an interest in [describe collateral] or who owe money under your agreement:
[Names of all other debtors and obligors, if any]
(4) A notification in the form of paragraph (3) of this subsection (a) is sufficient, even if additional information appears at the end of the form.
(5) A notification in the form of paragraph (3) of this subsection (a) is sufficient, even if it includes errors in information not required by paragraph (1) of this subsection (a), unless the error is misleading with respect to rights arising under this article.
Does that help?