Well presently ERP is has a good market and offers a good career path....
I have been working in SAP for 1.7 years now as a techincal consultant....
To begin with ERP you should first consider which domain you would like to enter i.e. Functional or technical....
Talking in terms of SAP
Functional later splits to further specialisations and modules and trust me you can master only one domain after working some years on it.... so choice of module would be your second consideration after you decide to become a functional consulatant...
Examples : MM - Material Management, SD - Sales and Distribution , FICO - Finance , PS - Project Systems, HR
Technical - Talking in terms of SAP
You have ABAP consultants , BW (data warehousing) , XI , HR ABAP, Workflow consultants
To begin with a ERP you could try to join a company offering ERP solutions and gain experience but problem is that they mostly look to experienced professionals so getting in as a fresher is tricky... Certifications can be done but are quite expensive and done only if you are sure of ERP as a career....
For functional some people join as MBA grads and gradually develop from there.... Or you could get actual industry (core) experience in say material management , warehouse , sales and gradually shift to SAP....