Suggestions for reaction conditions to prepare methyl 2,4,6-trimethylbenzenesulfonate
Are you following a literature procedure? It looks like you should be able to find a reliable method that you can reproduce. Some general hints for optimisation:


Use a base to mop up the $\ce{HCl}$ that is produced. Either an
organic base like pyridine (preferably) or triethylamine or you can use an
inorganic base like $\ce{NaOH}$ or $\ce{Na2CO3}$ under 
Shotten-Bauman conditions  i.e. as a biphasic aqueous-organic system
Increase the reactivity of the nucleophile. Methoxide is a much better nucleophile. You can use commercially available $\ce{MeONa}$ or you can create it by something like $\mathrm{^tBuOK/MeOH}$


EDIT: I am assuming OP tries to make methyl 2,4,6-trimethyl toluenesulfonate since he states that MeOH is a reagent.