The devī māhātmyam is an important text for devī sādhanā. There are many editions of this text, with variant readings and equally varied śloka numberings. In most texts, the numbering causes sentences to be split in unnatural places. This is probably because of a desire to effect exactly 700 offerings during homa. Two popular editions of the text are linked below:
Here is a new version of the devī māhātmyam. The text is the same as the gītā press edition, but it has been renumbered to avoid weird sentence fragments. The end result is śloka numbering which is quite similar to the nirṇaya sāgar edition !
If you are already using a gītā press edition (or some other edition) for caṇḍī homa, you can just make the changes in your existing text. Each pair of two-half verses is considered to be a śloka, and it resets after every "uvāca". There are a few exceptions where a logical shloka is a single half-verse. In the gītā press edition, these single lines are given below. When in doubt, look at the renumbered edition above for the śloka boundaries.
In kerala, devī is commonly worshipped through bhagavati seva, where she is invoked in a lamp. She is invoked in the primary lamp, and is worshipped along with ganeśa, and optionally the kula devatā. She is worshipped with the devī māhātmyam and lalita sahasranāma with many flowers and leaves. There is quite a bit of variation in the details of this ritual, as can be seen below.
In karnataka, a variation of this ritual called 'dīpa durgā namaskāra' is performed. It is basically the same ritual, but importance is given to the many namaskāras that are performed after the puṣpārcana. The maṇḍalas used outisde kerala tend to be more colourful, with blues, greens and pinks etc. The traditional kerala padmas are simpler, and stick to white (rice flour), yellow (turmeric) and red (kumkumum).