SMT reflow oven

Problem 
"I'm new in this industry and need a little direction. I have a wide verity of SM parts on a board, top and bottom. The larger components have a very nice reflow, good shine. The 0402/0201's has a dull almost cold solder look. The boards function and work properly but I am not satisfied with is look.
I have a Heller 7 zone oven that allows me to make a profile to match the kester solder reflow profile. where should I go for more information to insure a good product?"

Answers FYI
1.1 Profile Solution to Cold Soldering Cause for Cold soldering The peak temp of reflow is too low. The preheating temp is too high and it takes too long Solution Lower the preheating temp and increase the peak temp in the reflow zone
1.2 Profile Solution to Solder Bridges Cause for Solder Bridges The viscosity of melting solder during reflow is high Solder paste collapse during preheating Solution Lower the preheating temp a little and increase the peak temperature
1.3 Profile Solution to Solder Balls Cause for Solder Balls Preheating has not been done properly

Small paste deposits have less flux thus less flux activity to enhance the wetting. So preheat needs to be as short as possible, ramp to spike if possible. Try not to ramp hold and spike - pending thermal delta on product can be made to ramp to spike ok without hold phase.
If Paste is T4 or higher, and non N2 reflow, issue is worse as higher metal surface area is involved togather with lower flux amount.
If can increase paste volume with stencil design can try and balance this out a bit.
If have access to N2 reflow this helps greatly as solder paste deposits get smaller.
Of course the solder paste flux has influence one vs another - better activity in smaller amounts , but always trade off - more active flux can be issue in post assembly pending product intended purposes etc

Regarding the issue you are having with 0402 and 0201 components can be caused by factors such as: 1) Wrong solder paste type. 2) Insufficient flux. 3) Wrong profile, etc.