Critique..that i can.
First of all helmet. You do not paint bright colors atop of dark colors, it will appear very messy.
You first need to make and intermdeiate layer, that covers dark color ok and that will accept light color ok.
Second the best weapon of a beginner table top painter is washes and drubrishing. Browse internet for drybrushing. You should use wash on a Splinter Rifle.
Third - the model have an appearence of a very thick painted. Paint should be thinned more. About a consistency of milk, maybe slightly thicker. If you dont wanna trouble yourself with consistencies try search how to make a "wet pallet". This thing will improve your painting much.
Here is a book i bought some time ago, it covers the basics pretty well. Read page 16 about Base Colors.
The Dance of Death begins - embraces, caresses, and kisses,
The Harlequin loves you as you fall over in pieces!