it depends on the size of the kit,i use super glue on the seams to hold it into shape and then poly glue it after the super glue has dried,then i use filler to get rid of the seam,on something like this i drop a card dash floor and dash into the cockpit and then a rear bulkhead to mount the seats on,this will stiffen the weak front section,the wings are done in a similer way but i add filler where i plan to mount any parts [wings/undercarriage etc/ as this gives a strong point to mount to,on a large kit you can add bulkheads as per the real aircraft to stop any twisting,hope that helps