Ring Tone - Volume

I don't think theres a way to increase the volume, maybe the next best thing is to get a ringtone that is quite piercing sound but without being offensive. I am a bit hard of hearing but the the txt alert and normal phone alert I can hear ok if the phone is in other room. two that I use I got from here txt alert http://www.zedge.net/ringtones/986693/ring-flute1-ringtone/ titled Ring-flute1 and normal calls http://www.zedge.net/ringtones/355486/waterfall-ringtone/?pos=3&search=waterfall titled Waterfall. might not be to your taste but picking the right ringtone might help in hearing it better.

HTH

for a loud ringtone find a loud song and use http://makeownringtone.com with "Normalize" filter enabled

Keep in mind that the phone has a "Quiet ring on pickup" feature.  When the G-sensor detects movement, it'll assume you have the phone in your hand and reduce the volume a fair bit.

To make sure it's off :

Settings -> Sound -> check if "Quiet ring on pickup" is selected.  If so, de-select it.

As for my personal ringtone, I use a remix of "The Imperial March" from the Star Wars movies.  That's quite distinctive, so it attracts attention even if it isn't loud or intrusive.

You'll need to edit the file itself to make it louder... I use Nero Wave Editor, simply because it comes with Nero. Audacity is a good open source alternative, though