Helper grid or scene bounds in Unity 2D

I'm new to Unity and am trying to make some small 2D games to get the hang of the editor. I'd like to know if there's a way to toggle a helper grid on when in Scene mode so that I can position elements more easily on screen.

Also, if there's a way to put guides/helper lines on so that I know where the edges of my scene/screen will be whilst working, that would be super useful!

 

Morning, I had a bit of code that would use screen gizmos, might help u a bit.
I just made it to show me lines in a grid based on how high and wide, also what size I wanted the grid. Helped me a bit a while ago to try and get a rough idea of 2d screen real estate.
Hope it gives u a starting point to look at.

Code (CSharp):

1.    using UnityEngine;
2.    using System.Collections;
3.  
4.    public class DrawGridLines  : MonoBehaviour {
5.    
6.       public float gridSpacingX = 0.5f;
7.       public float gridSpacingY = 0.5f;
8.    
9.       public int blocksWide =32;
10.       public int blocksHigh = 24;
11.    
12.       public Vector3 gridCentre;
13.    
14.    
15.       Vector3 GetLowerLeftDrawPoint(int squaresWide , int squaresHigh ) // returns the starting point at the lower left point
16.       {
17.          float xPos =(float)( -((squaresWide * gridSpacingX)/2) + gridCentre.x);
18.          float yPos = (float)(-((squaresHigh * gridSpacingY)/2) + gridCentre.y);
19.          return new Vector3 (xPos, yPos, 0f);
20.       }
21.    
22.    
23.       void OnDrawGizmos ()
24.       {
25.          Gizmos.color = Color.grey;
26.          Vector3 lowerLeftStartPoint = GetLowerLeftDrawPoint(blocksWide, blocksHigh);
27.        
28.          float lineLength = blocksWide * gridSpacingX;
29.          for( int xLine = 0 ; xLine <= blocksHigh ; xLine++)
30.          {
31.             Vector3 vFrom =  lowerLeftStartPoint + new Vector3(0f,(float)(xLine * gridSpacingY), 0f);
32.             Vector3 vTo = vFrom + new Vector3(lineLength, 0f, 0f);
33.             Gizmos.DrawLine (vFrom, vTo);
34.          }
35.        
36.          // draw the vertical lines now
37.          lineLength = blocksHigh * gridSpacingY;
38.          for (int yLine = 0; yLine <= blocksWide ; yLine++)
39.          {
40.             Vector3 hFrom = lowerLeftStartPoint + new Vector3((float)(yLine * gridSpacingX), 0f, 0f);
41.             Vector3 hTo = hFrom + new Vector3(0f, lineLength, 0f);
42.             Gizmos.DrawLine (hFrom, hTo);
43.          }
44.        
45.        
46.       }
47.    }