In order of importance I'd say this summer we need:
1. Centre back (the weakest area of the team, improvement much needed)
2. Right wing (a slight weak link in the side)
3. Striker (more cover needed, there were times I looked at our bench and there was no attacker there who could come on and change the game. We could possibly get a left winger instead as that gives us the option to either play Rodriguez up top or on the left)
4. Centre midfield (we have good quality there but lack a little bit of competition/depth)
5 and 6. Cover in both full back positions (self-explanatory, our first choices are very good but we need cover for Shaw in particular. There may be youngsters coming through that can fill in)
You might put another centre back on the list as well but that depends on Forren. So if we got Astori and Nainggolan I'd say a right winger and a striker are next on the list.