Realistic or Fantasy Transfers

I'm about to finish my first season with Chelsea. Should be top four and due to all the high value players I don't use, plus what I've saved I should have about 2-300 million to spend for season 2.

I'm tempted to bring in the likes of Vini Jr but wonder if it might spoil my save. I don't want to be fully realistic (signing 20 yr olds on massive contracts) but I wondered what this sub prefers.