Interest rate, ensure that the interest rate you will be paying is lower than what you are paying for the current loans. Consolidate only the debt which have higher interest rate, normally these would be credit card debts which have high late payment fees and interest rates.
Shop around for the best deal, do not go for the first offer that comes along. Look for the consolidator which will charge you the lowest interest rate. Also ask about the possibility of discounting the amount of the loan if you are in danger of bankrupcy.
It would be better if you consolidated your debt as soon as possible, because as your credit rating falls the interest rate you need to pay will rise. So the sooner you consolidate your debt the better the interest rate since your credit rating would not be as bad.
Consider taking a secured loan since they normally have a lower interest rate as they are tied with some property as collateral which the lender has the right to sell incase of non payment. This will also motivate the borrower to make payments.
Try to pay off the loan as fast as possible, the longer the duration of the loan, the more costly it is. The monthly payments would be higher if paid over a shorter duration as compared to a longer duration loan but bear in mind this also means that you are paying more interest over a longer duration.
Change your life style, debt consolidation by itself will not help you get out of your debt. Live withen your means, i.e. spend what you earn and save some.