For my maps I've been recently using Kapil's Map Designer, you'll need to get used to the keys and how things work but it's worth the effort. I've tweaked his code to allow more precise movement and rotation, I can show you how if necessary. I know other filters are easier to use but for me personally I think it's great.
It may be difficult at first but it's just an option, do a search on the SA:MP forums for others if you like. Everyone uses different tools to make object maps. Another choice would be JernejL's Real Map Editor, it won't work for me now but it could be simpler to use than the filter by Kapil.