I would not recommend starting with Doing Grammar if you are not very confident with Grammar. I am going through this now and will post a detailed review about this in a few weeks.
I would recommend the following:
1.Either Wren & Martin or any other high school book - if you need more help with your basics
or
1. You can use the GMAT club grammar book (starts with more basics than KVF but could have a few things additional and is not as is not as comprehensive KVF
2. Kaplan verbal foundations (KVF)
3. Doing Grammar - (optional)
4. Aristotle SC grail &
MGMAT SC
I dont believe that Doing Grammar is absolutely required unless you have plenty of time in hand(if you do, lucky you !!) and would not start with it for sure - who ever said is a good starting point is not at a beginning level.
Good luck.