Many, many variables here. To answer your main question: a typical 2 pass shave of first wtg then second atg wont give a smother shave vs a single atg pass in terms of final result... You cant get much closer then atg regardless of how many pass or directions took place prior to it. What you achieve by starting wtg is an easier and more productive atg pass following it. Atg passes are pretty rough on your skin and hair, even with proper prep and technique, so eliminating as much hair as possible prior to (like starting wtg for example) drastically cuts down on pulling and irritation from your final atg pass.
With that out of the way...
I would ask you to clarify what you mean by "smoother" shave. Do you mean as in the shaving process being easier, more productive, and tugging less or do you mean like baby butt smooth, 100% hairless from skin level up, as the final result?
If you simply are trying to achieve a BBS dome and are not currently experiencing irritation then you can always add passes following what I mentioned above: do a full wtg around your head, rinse, re lather, then do a final atg pass all around.
If you are seeking to improve your shaving experience and process the biggest thing to start with is a good brush and soap/cream. Don't be fooled into thinking you need to drop a whole bill either. I have an omega synthetic brush and a maggard synthetic brush, both under $15 and both solid performers. As for soaps and creams I'll typically use proraso cream (about $10 a tube), la toja soap (about $6 a stick), or occasionally van der hagen soap which is about $2-$3. All of these last a long time and are well worth it. There also are hundreds of other soap and creams available so try everything you can! The main thing here is that the action of creating lather on your head with a good brush and soap/cream not only feels amazing and gives you levels of comfort and joy not found in any canned gel but it also works the lather under your hairs which in turn lifts them and hydrates them, all allowing for a closer and more comfortable shave.
From there I can reccomend using a double edge safety razor but there is a huge learning curve if you are not used to it. If you prefer cartridges then try different ones. I used to use dorco twin blade carts on my headblade and recently switched to personna twin blade carts. The difference is like night and day. All other variables remain the same except the brand of blade used and since theny shaves have been so quick and smooth I haven't even bothered picking up my de razors.