Are you on a Mac or a PC?
If on a PC, then I cannot recommend highly enough the combination of IMGBurn and Verbatim "Advanced Metal Azo" DVD+R DL blanks - avoid at all costs using DVD-R DL as it is not possible to set a manual layer break in -R DL discs and the break point will be automatically set to the middle of your data. With +R DL, you can set this manually.
How to do this?
If you are not replicating (which is a different animal requiring different tools) then this is now as easy as pie if you follow these rules:
1 - Do not attempt to set the layer break in Encore (you cannot do this until you have compiled the disc anyway)
2 - Output from Encore to a DVD Folder (it should create a Video_TS folder for you), making sure that you have added chapter markers in the main footage because these will be used to determine your layer break if it cannot be placed between timelines/playlists.
3 - Launch IMGBurn.
4 - (first run only) Open the settings and make sure the following options are set:
A - Build, Page 1 - File splitting Auto. Page 2 - Create Audio_TS folder (some players still require this even though it will usually be empty), under "DVD Video" check every box. IFO/BUP padding is critical. Most of the rest can be left as default, although personally I set the buffers to be quite large.
5 - In "EZ-Picker" mode, select either "write files/folders to disc" or if you want an ISO image, select "create image from files/folders".
6 - Point to your newly created "Video_TS" folder from Encore, fill in the ISO & UDF data fields, set the output location if making an image and hit the GO button.
IMGburn will then parse your folder and ask you to select your layer break from a list of all the possible spec legal places it has found. These can be previewed, and the ideal place is on one with a green star (between timelines). If necessary you can use a chapter marker location - preview here is highly recommended - and this will be set for you and the disc will be cooked.
Setting the break point used to be a nightmare - and for replication can still be aggravating - but for burned discs it is simples as long as you use DVD+R DL.