3x spells (don't go past 204 or 107 until you have level+21 in cleric spells)
1x harness
1x pf
1x religion lore (stick to religion until at least 30)
1x mana control

If theres something else you really want, trade a spell or two for it, but if you are going pure CS keep spells at least 2.5x and preferably at least 2.75x.

DEX isn't important.
Spirit for raising isn't important (because you'll have the full version at level 18)
...

Alternatively learn spell aim

2x spells (1x cleric, get 215 as a priority)
1x harness
2x SA
2x MIU (to 40 ranks or whatever it takes you to be able to always activate any wand)
1x pf
1x lore (summoning is the main lore for bolters)
3 ranks MOC (1 when you learn fire spirit or start waving ball wands, 2 around level 20, 3 around level 30)
1x mana control

You'll have some spare points. Put them in spells if you haven't any other pressing use for them.

DEX is important
Spirit for raising is important (because you'll only have the basic raise at level 18)