Since J2ME is a subset of java there should be no problem with you picking up J2ME first..
Some recommeded reading other than Nokia tutorials is:
Thinking in Java by Bruce Eckel(search fro the free online version via goolge)
Micro Java Game Development by Fox and Verhovesk
Java 2 Micro Edition by White and Hemphill
Wireless Java by Knudsen
Also register as JDC emmber at java.sun.com so you download the BOFs from JavaOne2001, 2002, 2003 on J2ME..yes they have sample code..
Best bet is to start out small do a casual game frist..one that you the end use rplay in free time with not many levels or complexity..
Money wise submit to lump sum 3rd party publishers such as Nokia first..those tha tpay per quarter to developer per download 2nd..
Use core MIDp1.0 features with othe rfeatue soptional to maximize porting for maximization of sales channel revenue..
For other tips there are at least 2 J2ME game coders doign tips and posting them to blogs that show up at javablogs.com....yes I am one of them
To get programmign book money sign up for free monthly contests at devicetop.com(they cover more itv stuff but alos J2ME for handsets)
bookmark all vendor handset dev forums and visit them regularly along with bug databses of J2ME at Sun and at handset vendors..
java.net(left sidebar..javagaming link go to homepage and click on forums they have a j2me section you need to register as free member)
Oh yeah one more point.. we at times get frustrated at coding difficulties and such..while we can yell at problems in forums.. make sure to treat your vendor handset tech reps like gold..they are valuable resources for both tech info/workarounds and the info you need to sell your games as they know what telecom operators are asking for..