Like CarbonSystem said, limit the amount of free revisions that the client can ask for the audio content. If they go past that amount then you can set a separate fee for the following revisions.
Communication with the developer:
First, always try to get as much material as you can from the developer team and go through it thoroughly. Game design documents, early concept art, rough animations and even playable builds really help you to get inside a project and start the audio design process. Ask a lot of questions!
Always try to be part of a project from day one. Opening the communication channel between you and the developer as early as possible is really important. When you are there from day one you can really influence the audio design of the project and get a lot of precious info that will help you to create high quality assets.
Time Management tips:
Plan and schedule your time. When you know what you are going to do each day and you stick to it then you won't run into any problems with the deadlines. I have had multiple projects at the same time and I could not have completed all of those without scheduling my time for each project. It takes some time from the start but it's totally worth it in the end.
You could utilize a simple version of an online Kanban board. Kanban board consists of three columns: "to-do", "in progress" and "done". You create your tasks and add them to the "to-do" column on the board. When you start working on a task you move it to the "in progress" column and when you have completed the task you move it to the "done" column. It is a really useful tool to keep yourself up-to-date what has been done and what needs to be done on a project.