There are two main shortcomings for a cross-sectional design using the same source.

1. common method variance: the correlations among variables can be inflated or biased because the same person assess all the variables. Changing the order of IV and DV cannot solve this issue. To reduce this bias, read the following article.

Podsakoff, P. M., MacKenzie, S. B., Lee, J.-Y., and Podsakoff, N. P. (2003), ‘Common method biases in behavioral research: A critical review of the literature and recommended remedies,’ Journal of Applied Psychology, 88, 879-903.

2. causality: we cannot test the causality with a cross-sectional design study. If you assess DV first, this will cause more problems in terms of causality.

I strongly suggest you to use a time-lagged design (e.g., assessing IV first, after at least two weeks or one month assessing DV.).

Thanks a lot Tae-Yeol Kim for the information. I had gone through the paper Podsakoff et al., 2003 and I do understand the issue of common source bias and the issue it can raise regarding causality.but as the current data stands, collecting data at two times is not a possibility so the only option I had was to look at minimize the bias.

In  constructing  a questionnaire it is highly  recommended to  put the  sensitive  questions at the end of the instrument such as asking personal and demographic charactristics

But if you mean by independent variables other variables such as past behavior  or  habbits or activity or life style then it does not make difference if they are asked  before  or   after  the dependent variable 

Thanks a lot Abdulrazzak Charbaji and Christian Fischbach for your inputs. I will definitely go for Harman’s single-factor test. Also inputs on position of profile questions is a good idea.

Insofar as the common methods / single respondent issue, the point is that respondents may "guess" the relationships being studied. Placing the dependent variable early in the survey helps reduce this by if is not obvious which it is.

Regarding common methods in general, I would encourage you to look well beyond the Harman test, which has poor psychometric properties and is increasingly considered insufficient evidence. For an overview of solutions, some of which you can implement during study design, see Appendix C and text of:

Krishnan, R., Martin, X., & Noorderhaven, N. G. 2006. When does trust matter to alliance performance? Academy of Management Journal, 49(5): 894-917. (Available at http://scholar.google.com/scholar?oi=bibs&hl=en&cluster=3292640590399664878 or via request.)

My little comment is that you should collect information on both independent and dependent variables at the same time. If information on either one is collected, how will you identify individual respondent on the instrument? So, the two should be at the same time