If there’s any mathematics in your application, check it; typographical limitations can cause very embarrassing errors which are harder (read: takes more time and thus more money) to correct once the process has started. Look for the same language in the specification (particularly, in the ‘Detailed Description of the Invention’) and the claims.
Read the claims, and ask yourself (last chance!) if you could design around that language, and still make your invention work. Is there an element which can be left out of the ‘base claim’? Is there a necessary element which has been left out of the base claim? If you see a word you don’t understand, get help for your new invention idea. It may be a bit embarrassing for you now, but it’s a lot more expensive, as well as embarrassing, if the jury doesn’t understand it later.
Look over the drawings, and don’t just nod and smile politely; if they don’t describe what you’ve invented, they need to be corrected. Finally, and most importantly, read through for the description of the “Best Mode”. If you’ve discovered a better way to do your invention, now’s the time to put it in.
However, there’s also as with most other engineering efforts, a time to ‘shoot the engineer and ship’. You may be facing a deadline (i.e. if you don’t file, you lose the right to do so); you may be being too perfectionist (you know there’s a better way but haven’t proven it is yet), you may be nervous (‘my name is going on this?’), or you may just want to spell-check the document one last time against the on-line Dictionary…but every minor change at this point is very costly, in both dollars and time. Keep that in mind, and don’t complain if your bill exceeds the estimate after three-or-more ‘final’ drafts!
What to do with new ideas about the invention have before the application is filed, but while it is being prepared?
Prepare them much as you did the initial application (description, context, drawings, goal, function, pros-and-cons) and send them on to the patent attorney. You may be changing the scope of your invention — and if they’re big enough changes, you may force a complete re-start to the entire process. Be ready to discuss whether the addition is worth including, however; and don’t believe that every change will be added. Because sometimes the patent attorney has already thought ahead or come up with a general-enough description that your addition is already covered as explained in this article – https://www.kstatecollegian.com/2021/09/24/how-you-can-boost-the-chances-of-becoming-a-successful-inventor-with-inventhelp/.
What to do with new ideas about the invention have after the application is filed?
Do talk about them with your patent attorney. But don’t expect that they can just be ‘crammed in’. Even though the USPTO is currently working with a two-to-three year backlog (meaning you won’t hear a first response from them until nearly three years after the application is filed), your filing date ‘fixes’ the date of your invention; anything substantively new past that point counts as “new matter”. And the USPTO generally will not allow any “new matter” to be included in your application. Because they have a whole class of applications (with fee) for what are called ‘continuations-in-part’, devised for just this sort of inventiveness.