Blogging is your opportunity to connect with readers. Building a relationship of trust with them is critical. Therefore, you should never lie or exaggerate your income, popularity, stats, subscribers, or anything else on your blog.
However, you can also be too honest. For instance, blogging about your lack of experience as a blogger, or the fact that your site is new and does not have a big following yet would both be something you don't want to mention -- either directly or indirectly.